Take the Navy SEAL Underwater Knot Tying Test

by A Manly Guest Contributor on July 26, 2012 · 27 comments

in Manly Skills, Outdoors, Survival

Editor’s note: This post is based on a series that was written by the ITS Crew and originally ran on ITS Tactical.

Potential Navy SEALs face many challenges during BUD/s (Basic Underwater Demolition/Navy Seal Training) as they become schooled in swimming, diving, parachuting, and enduring grueling physical exercise. Another challenge every candidate must complete is the Underwater Knot Tying Test. During the first phase of BUD/s, students are taught five knots–the Bowline, Square Knot, Becket’s Bend, Clove Hitch, and Right Angle–which they’re required to tie one at a time underwater, each on a single breath hold.

How would you do on this test? Why not take it yourself and find out? Below, we provide instructions in both photograph and video form on how to tie the five required knots, and then set down the test conditions you’d experience at BUD/s, along with a video demonstrating how the test is performed.

Knot Tying Line

Underwater Knot Tying 02

All knots tied during the test are with the BUD/s student’s knot tying line that he’ll have with him at all times during BUD/s until completing the Underwater Knot Tying Test.

The rope used at BUD/s is just common nylon rope that usually measures 5/16″ diameter and is around 20″ in length.

Students are encouraged to practice their knots whenever they can fit it in during their days at BUD/s to prepare themselves for the test.

Knot #1: Bowline » Loops

(Strength: 2/Secure: 2/Stability: 4/Difficulty: 3)

Please refer to this post for a description of what these ratings mean.

Before we continue any further we’d like to clear the air on how to properly pronounce bowline. This knot comes from the need for attaching sails to the bow of a ship for stabilization, and is pronounced “bow” like a ship’s bow, not “bow” like bow and arrow.

The Bowline Knot was originally used for the purpose just mentioned, but has progressed to include a host of other uses today.

Nowadays, you’d most likely see a Bowline used for mooring a small boat to a pier or in rescue applications when a fixed loop is needed that won’t close around a waist or foot.

In rescue applications we highly suggest, due to the somewhat unstable nature of the Bowline, that a half hitch is added to the knot at the very end to further secure it.

If the Bowline is not kept under load, it can easily come untied which is why we recommend the extra half hitch (we’ll explain below).


  • Mooring a small boat to a pier
  • Emergency applications where a fixed loop is needed
  • Joining two ropes bowline to bowline (there are better ways to join ropes though)

Tying Instructions:

  1. Create a bight in the rope, forming a “q” shape
  2. Ensure that the “q” is made overlapping the standing part of the line
  3. Your working end will be wrapped around whatever you’re tying on to
  4. Create a loop and feed the working end through the underside of the “q”
  5. Bring the working end around the back of the standing line
  6. Continue passing the working end back through the “q” running parallel with the loop
  7. To tighten, pull the loop and working end with one hand, and the standing line with the other
  8. For increased security, create an overhand knot in the loop with the working end
  9. Pull the working end to tighten and finish the Bowline

View the gallery or YouTube video below and follow along with the steps above!

Bowline 01Bowline 02Bowline 03Bowline 04Bowline 05Bowline 06Bowline 07Bowline 08Bowline 09Bowline 10

Knot #2: Square Knot » Bends

(Strength: 2/Secure: 2/Stability: 1/Difficulty: 1)

Please refer to our this post for a description of what these ratings mean.

Yes, the Square Knot is a somewhat simple knot, but the primary purpose of teaching this knot at BUD/s is for demolition.

When working with Det Cord (Detonation Cord), lines need to be spliced together. The simplest way to do this is with a Square Knot.

It’s debatable whether or not to back up the ends when dealing with Det Cord. It burns from one end to the other when ignited and is basically just cord with a PETN core that burns at a calculated rate.

When the Det Cord burn reaches the backed up portion of the Square Knot, it will start burning not only towards the center of the knot, but also take off in the direction of the tail. This is why some don’t back up the knot.

At least a six-inch tail must be left after tying the Square Knot to prevent moisture from entering the Det Cord through the exposed end.

During the BUD/s Underwater Knot Tying Test, it’s not required to back up the knot.


  • In demolition to splice Det Cord
  • One of the most common knots in surgery
  • Used in first aid to tie bandages, as it lies flat
  • Tie boot laces to prevent boots getting pulled off by mud

Tying Instructions:

  1. Pass the right end over the left end and back under the left
  2. Pass the left end over the right end and back under the right
  3. Check the knot (the two loops should slide on each other, if not you have a granny knot)
  4. Tighten by pulling both strands on each side of the knot
  5. Back up the square knot by making an overhand knot using the working end of each side of your knot

View the gallery or YouTube video below and follow along with the steps above!

Square Knot 01Square Knot 02Square Knot 03Square Knot 04Square Knot 05Square Knot 06Square Knot 07Square Knot 08
The video below shows an alternate way of tying the Square Knot:

Knot #3: Becket’s Bend » Bends

(Strength: 2/Secure: 2/Stability: 2/Difficulty: 2)

Please refer to our this post for a description of what these ratings mean.

There’s a method to our madness in showing the Square Knot before the Becket’s Bend, as the two are tied similarly.

Much like the Square Knot, the Becket’s Bend is used to splice together two lines of Det Cord when working with demolitions.

The Becket’s is more secure than the Square Knot in certain applications. To add additional strength to the knot, a second turn can be added with the working end when tying.

As with the Square Knot, a six-inch tail must be left in both ends after tying. This prevents moisture from entering the Det Cord through the exposed ends.


  • In demolition to splice Det Cord
  • Joining two ropes of unequal diameter

Tying Instructions:

  1. Form a bight in the standing end, ensuring that the bitter end is hanging down
  2. Insert the working end through the backside of the bight
  3. Pass the working end around the back of the bight
  4. Tuck the working end behind the working part of the line
  5. Tighten by pulling the bight, the working part and the working end of the line

View the gallery or YouTube video below and follow along with the steps above!

Becket's Bend 02Becket's Bend 01Becket's Bend 03Becket's Bend 04Becket's Bend 05

Knot #4: Clove Hitch » Hitches

(Strength: 4/Security: 2/Stability: 4/Difficulty: 3)

Please refer to our this post for a description of what these ratings mean.

The Clove Hitch is an especially important knot taught at BUD/s, and also has its purpose rooted in demolition.

A Clove Hitch is the preferred knot to fasten Det Cord to underwater obstacles, linking them together in a chain for demolition.

During WWII the NCDU’s (Naval Combat Demolition Unit), the predecessor to UDT’s (Underwater Demolition Teams) and eventually Navy SEALs, cleared the beaches for the Normandy invasion.

You can bet that Clove Hitches were used during Normandy, just like they’re still used today. Anyone interested in a great article about the background of Navy SEALs, visit this link.


  • Linking obstacles together with Det Cord for demolition
  • Securing a rope to a post
  • Temporary tie in to an anchor point
  • A brake or check of an unwieldy object

Tying Instructions:

  1. Begin by wrapping the line around the post
  2. Cross the working end on top of the standing part
  3. Continue passing the line around the post working in the opposite direction of the first wrap
  4. Feed the working end under the standing part of the second wrap
  5. Clean up the knot by squeezing the two loops of the clove hitch together
  6. Tighten up the knot by pulling on the working end and the standing end
  7. *Ensure that there is a least a few inches left in the working end after tying*

An alternative method of tying the Clove Hitch is tying it on the bight, which means that it’s tied without having either working end available.

(This additional method is also shown in the video, but not the photos)

  1. Form two back-to-back, or opposing loops, on the bight
    (Similar to the Sheepshank)
  2. Stack the right loop on top of the left loop
  3. Place the stacked loops over a post or into a carabiner
  4. Tighten up the knot by pulling the two ends

View the gallery below and follow along with the steps above!

Clove Hitch 01Clove Hitch 02Clove Hitch 04Clove Hitch 03Clove Hitch 05Clove Hitch 06

Knot #5: Right Angle » Hitches

(Strength: 4/Secure: 3/Stability: 4/Difficulty: 3)

Please refer to this post for a description of what these ratings mean.

The Right Angle is a knot that is typically used as an alternate to the Clove Hitch, which we just covered.

When used, the Right Angle creates a more secure knot than the Clove Hitch, and if you know how to tie the Clove Hitch, you know how to tie the Right Angle.

As mentioned above, the Clove Hitch is the preferred knot to fasten Det Cord to underwater obstacles, linking them together in a chain for demolition. The Right Angle is used if you have multiple obstacles which would be linked to a ring main, or main line of Det Cord. To link each obstacle’s Det Cord lead to the ring main, a Right Angle is used.


  • Attach an explosive charge’s Det Cord to the ring main
  • Securing a rope to a post
  • Temporary tie in to an anchor point
  • A brake or check of an unwieldy object

Tying Instructions:

  1. Begin by making two turns around the post with your line
  2. Cross the working end on top of the standing part
  3. Continue passing the line around the post working in the opposite direction of the first two turns
  4. Feed the working end under the standing part of the third turn
  5. Clean up the knot by squeezing the loops of the Right Angle together
  6. Tighten up the knot by pulling on the working end and the standing end
  7. *Ensure that there is a least a few inches left in the working end after tying*

View the gallery below and follow along with the steps above!

Right Angle 01Right Angle 02Right Angle 03Right Angle 04Right Angle 05Right Angle 06

Test Conditions

At BUD/s, the Underwater Knot Tying Test is performed in the 15 ft. section of the CTT (Combat Training Tank), where students must swim out to a waiting instructor who is treading water over trunk line on the bottom of the CTT.

Upon reaching the instructor, students tread water while sounding off with their name, rank, and which of the five knots they’ll be tying.

One knot is tied at a time to a trunk line or stationary rope, and the student and instructor tread water between each knot that is tied.

After sounding off on which knot he’ll be tying, the student gives the waiting instructor the downturned thumb signal to descend. The instructor will return the signal, and the student and instructor will descend. The student must descend without splashing the surface of the water.

Upon reaching the trunk line on the bottom of the CTT, the student ties the specified knot and signals the instructor with an OK sign. The instructor then ensures the knot is tied correctly and returns the OK sign.

The student then unties the knot, grabs his rope, and signals the instructor with an upturned thumb to ascend. The instructor returns the signal, and the student and instructor will ascend.

After reaching the surface the student and instructor will tread water again as the student sounds off with the next knot he’ll be tying, and the process repeats itself.


Some things that will cause a student to fail:

  • Tying a sloppy knot or not dressing the knot before giving the OK sign to the instructor
  • Incorrectly sounding off on the surface, or stating they’ll be tying a knot they’ve already tied
  • Tying the wrong knot underwater
  • Running out of air and shooting up to the surface like a Pegasus missile, which while funny looking, doesn’t make the instructors happy

If the student does run out of air underwater, he’s instructed to give the slash across the throat sign for out of air, followed by the upturned thumb to ascend.

In the video below we’ve recreated the BUD/s Underwater Knot Tying Test, so you can see how it works:

Note: Because photos of the BUD/s test are not available, the photos above depict SWCC (Special Warfare Combatant Crewman) students training, who take the same test, in the same pool as SEAL candidates.


ITS Tactical (Imminent Threat Solutions) is an awesome website run by Military Veterans and those serving in the Special Operations community that covers skill-set information, tactical gear reviews, and DIY projects that can help you live better and survive any scenario. Check ‘em out and become a member!


{ 27 comments… read them below or add one }

1 Stephen Keenan July 26, 2012 at 4:11 pm

Great post, apart from one thing, bowline should be pronounced with ‘bo-lin’ as in ‘bow and arrow’, even though it is nautical, because a ‘bow line’ is a specific mooring warp.

2 Paul July 26, 2012 at 4:11 pm

Literally just did this a week ago at a Navy SEAL prep course. I was having trouble with it, but eventually got it. Just make sure you have someone watching you and making sure you’re doing it right.
When we did it, we started at one end of the pool then swam to the line where you tied the knot on, tie it, was inspected by the instructor, then you undo it and surface once given the “Ok” sign.

3 MrF July 26, 2012 at 4:50 pm

If they were in any way serious about this, they’d make them tie a Square Lashing, Turk’s Head or even a Pineapple Knot.

4 Rob July 26, 2012 at 5:50 pm

When we were in the scouts we used to race each other in tying the bowline one-handed. Actually, its a lot easier than with 2 hands and fun. My best time was 1.3 seconds.

5 Hope July 26, 2012 at 6:30 pm

I know a young woman who is in the process of applying to serve as a Navy SEAL. She is as brave and skilled as any man. I, on the other hand, break out in a sweat when I think about an underwater test!

6 JR July 26, 2012 at 9:59 pm

Hope, you are almost certainly mistaken. Women are not allowed to become Navy SEALs.

7 Andrew July 27, 2012 at 12:20 am

Becket’s Bend is more commonly known as a Sheet Bend also. I was a little confused at first until I looked it up!

8 Dan July 27, 2012 at 6:19 am

And the square knot is more commonly known as the reef knot

9 Caleb July 27, 2012 at 9:33 am

As Andrew said, “Becket’s Bend” is better known as the “Sheet Bend.” The”Right Angle” is better known as the “Rolling Hitch.” In years of teaching knot tying I’ve never heard it called the Right Angle, but it does describe how it overcomes the shortfalls of the Clove Hitch.

I’m surprised they don’t go all the way British with their terms and call the Square Knot the”Reef Knot.”

These knots are easy to tie but not always the strongest or best choice. I expected more from our premire combat team.

10 Mark Ruddick July 27, 2012 at 11:42 am

The first four know are the basic ones we teach to our cubs (8-10 years old). Although they don’t have to do it underwater. It is nice to see that the fundemental knots are used all the way up. I’m going to show the cubs this next year when they ask about tying knots. I wonder if the Seals train with licorice ropes?

11 Sean July 27, 2012 at 12:17 pm

Me too about the sheet bend.

This actually sounds like fun. i have to find a pool to try this out (i’d guess a public pool would object to me swimming underwater with rope)

12 Rick R. July 27, 2012 at 12:27 pm

If you’re interested in knot tying, have a look here: http://www.animatedknots.com/

13 Tecumseh July 27, 2012 at 10:13 pm

Respectfully I must agree with the first commenter; the correct pronunciation of the bowline is “bo-lin”

Wonderful post!

14 Andreas S. July 28, 2012 at 5:30 am

We did something similar at the Danish Navy Diving School. There we had to do all 5 in one breath, but the instructor went down afterwards, so you didn’t have to wait for confirmation from him or untying the knots.

All in all it might even be harder to do the SEAL test as it takes longer, and you have to move up and down a lot…

15 beenthere July 28, 2012 at 10:03 pm

The point of this event is to gauge a persons ability to remain calm underwater, not to tie the actual knot. What this article leaves out is the mental stress each student is under and the unrelenting harassment from the instructors. When the student is done tying the knot, the instructor will take his sweet time checking it over. For most students the tying of each knot takes 15 or so seconds, but the instructor may take 45+ to check it. The first couple of knots are no sweat, but the 3rd, 4th and 5th knots can be problematic. By the time the instructor is done checking the knot you are most likely doing the funky chicken. The other thing to keep in mind is that you will get punished if you use the trunk line to keep you at depth.

16 beenthere July 28, 2012 at 10:08 pm

One other item, this event is one of about 14 for that day. The trainees may have just completed a 2 mile open water swim then had to run the mile to eat. Then before actually doing the knot tying, the team may have had to do countless push ups, squats or other exercise.

17 LPB July 29, 2012 at 12:44 pm

There, there, caleb. Let me try to ease your diminished expectations.

I think we all probably know that IF you led a “premiere combat team” (instead of just teaching people how to tie knots), the knot tying test in the basic course would be infinitely more difficult than this.

I’m almost certain that you would “drop” a guy who could run, shoot, swim, and paddle with the best of them if couldn’t execute a perfect jury mast knot (and no, I don’t care what the English would call that) on one breath, and that’s after braiding his own line out of filament threads.

Talk about “knot” being able to see the forest for the trees…(eyeroll and walk away).

18 LPB July 29, 2012 at 1:03 pm

Ooooh, watch out the C.A.L.E.B. Team. Nobody thinks they’re much good at anything that would harass or kill the enemy, but if you ever get into a knot-tying contest with them, you’ll be sorry!

19 Jeff Asher July 29, 2012 at 11:10 pm

These are all good basic knots that everyone should know. They come in handy securing a load in the back of a pickup as well as the other uses mentioned above. I tie the one-handed bowline pretty often as I am a competitive sailor and usually perform bowman duties. I’ve taught pioneering for the boy scouts in the last few years and knots are a hobby for me. I carry 10 feet of cord in my briefcase and practice knots when I’m bored or between meetings sometimes. The TSA has never had a problem with the cord going through a checkpoint at an airport either.
I haven’t tried it, but all 5 on a single breath should be pretty easy, event without goggles or a mask. Not sure about the SEAL test conditions though. That sounds a lot worse.

20 Jerrad August 3, 2012 at 1:27 pm

After reading this post I felt a little…knotty.

If you want to spend a day with a rope and a good book, I suggest Ashley’s Book of Knots. ~3000 knots, their history, their uses, and how to tie them.

21 Dave August 5, 2012 at 1:47 pm

I learned those knots as a cub scout (not underwater). It was very helpful to already know them when I was in the Navy, as a diver, and later as a Firefighter. As A FF, we used to practice tying them while wearing heavy fire gloves, then later doing it blind-folded. That was stressful enough without holding your breath.

As Beenthere said, it’s not as simple as it may sound. there’s a lot more happening leading up to that type of evalution. The primary goal is to maintain your composure under stress while doing an otherwise simple task. Any 8 y/o can be taught to tie a knot. Being able to do it when the instructors artificially jack up the stress levels is where the difference lies.

I was not a SEAL or SF member. I did some tough training, but nothing compared to those guys. I have had the priviledge to call several of them friends, and my son is training to be among them (God willing). I have the utmost respect for those guys.

22 drbitboya August 10, 2012 at 8:56 am

These guys have my deepest respect, too.

I am pretty sure I could do all these on one breath underwater (and blindfolded and behind my back) on my own, and I’ve also done them under the (relatively mild) stress of sailing competition. But I suspect it would take several tries, if at all, to do even one under the stress described.

Thanks for the new name for the Right Angle; I learned it as Rolling Hitch but also as the Taught Line hitch where it is used to tie a line back along itself. It is used when the strain is along the trunk. Also, it is more secure when the second wrap (hitch) is wedged between the first hitch and the standing part.

The Becket Bend and the Bowline are the same knot: a loop (where the line crosses itself) and a bight (where the line reverses direction but does not cross itself). The Square Knot is two bights. I learned the name Carrick Bend for joining two loops.

A Double Sheet Bend has the loop do a second wrap around the bight, similar to the difference between the Clove Hitch and the Right Angle.

The Square Knot should be used only when the two lines are the same. The Becket (or Sheet) Bend can be used when they are the same but must be used when they differ; the bight should be stiffer (typically larger diameter) line of the two and the loop the less stiff line.

Minor nit: the six-inch tails don’t keep water from getting into the cord (it must get into the card at the ends of the tails). It keeps water from getting to the *functional* part of the assembly i.e. to the knot that is part of what will burn.

23 Steven C. August 11, 2012 at 10:47 am

Try doing this without sleeping for a few days and after your body has been overworked to the point of complete mental exhaustion. Dexterity is lost making tying a simple bowline really difficult

24 Brian White November 12, 2012 at 11:43 pm

Your assumption of how to pronounce “bowline” is incorrect. I will refer you to Mr. Webster [ http://www.merriam-webster.com/dictionary/bowline?show=0&t=1352783917 ]. I am retired from the US Navy, and in all of my 60 years of living have never heard it pronounced your way. Ask a US Navy Seal to pronounce it for you.

25 Richard December 27, 2012 at 11:57 pm

Ahhh…. This takes me back to being 21 on Coronado. Good but miserable times. I remember hoping fences into condo complexes to use their pools to practice these on our days off from training. And yes, it’s a pronounced “Bo-Lin” even though it is spelled Bowline.

26 SN February 14, 2013 at 3:41 pm

Knot tying is a good skill and discipline for anyone to masters. Armchair quarterbacking who is an elite operator and who isn’t is ridiculous. Caleb, feel free to join me in the pool anytime, and I’ll show you what the difference is between tying a knot – and Water confidence knot tying.

The purpose of the knots are not the knots themselves, but rather fine motor skills while in a hypoxic state. Controlling panic and relaxing while executing a slow, smooth task is the requirement. When I did my pool training (different school, same umbrella), our knots were square, Girth hitch with an extra turn, Bowline, Clove hitch, and Double Fisherman’s knots.

Every dive team learns knots that are important for their specific mission (i.e. rescue vs demo vs salvage/repair). Also, the reason it is difficult to make it happen is because you are treading water with your hands over your head to “show your ropes” prior to being “allowed” to go subsurface and execute the knots. I never had the benefit of a mask, and DID have the benefit of some MilSpec chlorine pool water.

Did anyone else wonder why the Crossfit shirt guy was so skinny? Maybe less kipping pullups and more meat would help. SN

27 Some Sailor June 5, 2013 at 9:17 am

I would be the last to criticise the Navy Seals and the vital, difficult job they do. If they want to pronounce bowline “rumple-stilt-skin” that’s fine with me. But I don’t believe that they do.

A sailor would call it a bo-lin, no question about it. I crew some of those square-riggers that you see in the movies, including the one that famously sank recently. I also play a pirate on TV. What more cred can you ask for than that, arrr?

The bowline is not a terribly strong knot. It stresses the line more than others, and will fail sooner under heavy service. I have seen experienced sailors use the bowline to bend a line to an anchor, which just makes me cringe. Please, don’t use this knot for anything important!

Yes, the bowline is often referred to as “the sailors knot”, and we do use it in places, but not as often as you might imagine. Mostly it’s just for lanyards and small grab-lines. When we need to bend to something important, we’ll generally use a round turn and two half-hitches.

The key to tying a proper bowline is to leave plenty of tail, and make certain that the tail exits the knot inside the loop as shown in the photos, not the outside. Also, take some time to fair it up properly. An “insurance” hitch is okay, but if you need one, why are you futzing around with a bowline in the first place?

Your square knot is fine, but we’ll more often call it a reef knot because it’s commonly used in reefing down a sail. Put a loop in one of the tails for untying quickly and it’s called a “slippery reef”. I guess your shoelace knot would be a double-slippery reef, but I’ve never heard the term used.

Something the article should have stressed is that the tails should parallel the line when finished. If you find your tails coming off at an angle, you’ve got yourself a treacherous granny knot, a blatantly obvious sign that you are a hopeless lubber.

The extra two overhand knots for insurance are fine, but then what is the square knot for? Just tie the two overhands alone, draw them up together, and you have the fisherman’s knot, a much more secure way to bend two similar lines together.

Your Becket’s Bend is what we would call a sheet bend, also used to bend to a loop or a grommet. Simple, yet very strong. Make sure both tails are on the same side. You can take a second turn for an even more secure double sheet bend.

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