Failed 25m underwater swim.

[Angelo Farina]

When I certified for Cmas instructor the requirement was an underwarer swim of 33 meters, with one turn-back at the end of the 25m pool.
No mask, no fins, no suit, no weights. Mandatory style: underwater breast stroke (quite different from normal surface breast stroke).
At the time I was capable of 50m...

 

[Landau]

Former swim instructor here. Technique is equally important to breath holding ability. Make sure you are perfectly steamlined it can make a big difference.

 

[lehele]

No idea, never thought to count them but I'm gonna go with 20ish no fins.

1m per second is the standard freediving speed in the pool, more if you are allowed to push off. My pb was 100-ish meters in around 1:20.

SSI divemaster

 

[lehele]

25 meters in 30 seconds? Underwater? Even 45 seconds if pretty quick.

I swim masters in a 25 meter pool 2 to 3 times a week. What agency requires a 25 meter underwater swim?

SSI divemaster

 

[boulderjohn]

A tiny bit of practice and decent pair of freedive fins should allow just about any healthy person to do a 25 meter apnea swim in a pool. With decent fins and technique, it should take around 30 seconds or so. As you get better at it, slower is easier and it might help to wear a little lead on a belt; if that is allowed.

Please do NOT practice apnea in a pool without direct supervision.

The problem with all tests like this is they are, as this post suggests, impacted by the equipment used. I pointed this out to my instructor when I was doing the 800 meter swim for my divemaster certification. My time depended significantly upon the model of the fin I was using. That means it spoke at least as much to my equipment choice as my swimming ability.

 

[lowwall]

When I certified for Cmas instructor the requirement was an underwarer swim of 33 meters, with one turn-back at the end of the 25m pool.
No mask, no fins, no suit, no weights. Mandatory style: underwater breast stroke (quite different from normal surface breast stroke).
At the time I was capable of 50m...

When I was swimming competitively in the 1980s. I did 50 yard (45.72m) underwater swims regularly. That's two lengths of the old US standard 25 yard pool. I did 50m once in high school during a warmup at a meet at the pool they built for the '84 Olympics. My longest underwater swim was 200 feet (61m) at my 100 foot college water polo pool.

I also used to practice holding my breath while sitting on the lifeguard stand (pool only, I didn't do this at the beach). My best was 3:30. Nobody I knew back then could come close to matching me so I thought I was the best. And then years later, I found out what the real apnea swimmers could do

For example, here's the old 244m no fins record. The same guy later pushed it to 250m. Notice the technique, big pulls and lots of glide.

 

[BlueTrin]

When I was swimming competitively in the 1980s. I did 50 yard (45.72m) underwater swims regularly. That's two lengths of the old US standard 25 yard pool. I did 50m once in high school during a warmup at a meet at the pool they built for the '84 Olympics. My longest underwater swim was 200 feet (61m) at my 100 foot college water polo pool.

I also used to practice holding my breath while sitting on the lifeguard stand (pool only, I didn't do this at the beach). My best was 3:30. Nobody I knew back then could come close to matching me so I thought I was the best. And then years later, I found out what the real apnea swimmers could do

For example, here's the old 244m no fins record. The same guy later pushed it to 250m. Notice the technique, big pulls and lots of glide.

He is ridiculously good

 

[boulderjohn]

Then we can discuss why this test is so critical for someone wanting to teach scuba diving.

 

[lowwall]

Back to the OP's question. You can break this down to two parts: the immediate pre-swim prep and then technique during the swim.

The real key to this comes before you put your head underwater. You want to be as calm as possible. If you are in a pool, lean against the side, close your eyes and slowly breathe from your diaphragm. Concentrate on long, complete exhales and deep inhales. Finish with a deep inhale and push off with your arms forward, Superman style.

While finning, keep your upper body still and kick turnover low. It's all about minimizing effort and keeping the heart rate low. If you start feeling anxious, you can very slowly start to exhale. Just let the bubbles trickle out. Resist the urge to sprint for the end at least until the last 5 meters.

You can fiddle with fin types and technique, for example dolphin kick might be more efficient than flutter, but focusing on the above should get you there with pretty much any setup.

Note: this is what works for me. If any of this contradicts whatever actual apnea instructors are teaching now, then go with their advice.

 

[sea_ledford]

We have all of our academic dive classes do 25M underwater swims as part of the swim test. Everyone from OW students though Dive Masters. No mask or fins, no push off, but they can wear goggles if they have them. 90% of them don't have any problems with it, outside of anxiety about doing it. For the OW students, it isn't a requirement (we default to the SDI standards for that), but it is part of a grade.

If you are making it more than half way, it really is just about getting comfortable with being uncomfortable. If you are coming up before the halfway mark, you'll need some technique work, as well as some fitness for the task.

Long slow pulls is the best option, but I've seen plenty of people just power though with a rapid flutter kick (no idea how they make it). I like to stay just off the bottom, like nose 6 inches off the tile. Just watch the tiles go by, and once you hit the T, it's time to go up! Warm up runs help a lot too. Mammalian Diving Reflex is a real thing, so you'll get better at holding your breath by just holding your breath. Do some surface dives, swim around on the bottom a few times without worrying about distance or technique. You are just getting some breath hold time underwater.

Another drill to do that will help is doing underwater 50m swims with specific breath counts. 4 is a good place to start, so take one breath in the middle of the the first 25, one at the turn around, and 2 on the way back. By "breath" I mean one breath, so exhale underwater, take one inhale at the surface then back underwater. Once you get comfortable with them, 3 breaths is pretty easy. and doing them back to back with a couple minutes rest between should be no problem. If 4 is too much, try 5 (2 out, one at the wall, 2 back).

If you are really floaty with a full lungs, a weight belt helps a lot.