Strangely, sometimes the simple things take the longest to understand. You see, this review has been a long time in the making. I picked up the Finis Swimmer's Snorkel, and also their Freestyle Snorkel, to test out in the pool. I thought the concept was great - if you can practice your swim form without needing to move your head for air, the improvement you getting from keeping your center still should carry over to regular swimming. That's the concept, but the execution turned out to be more complicated than I had thought.
For one thing, getting set up with the snorkel is a bit of an ordeal. It's simple enough - a rubber strap goes over your forehead, and the snorkel comes down the center of your face to your mouth. But adjusting the height of the snorkel so that your mouth is in just the right spot can be tricky. And you have to pull the forehead strap VERY tight to avoid the snorkel moving while you're swimming. If you don't, the snorkel will go all wonky when you do a flip turn, and tilt to one side or the other when you come up, causing drag that will pull on your head. It's tricky.
Moreover, the technique of swimming with this beast requires more thought than you might think. For me, despite having been a swimmer, and some-time ocean snorkler, swimming with either of these contraptions had me taking water in my nose and mouth. You have to perfect the breathing technique with these guys, and in fact, breathing is 50% of what the snorkels are meant to train. Not so much in technique, but rather in strength. It's not easy to breathe with these! After your first 50 yards, you'll find yourself more out of breath than you think, despite the fact that you can breathe whenever you want to. Well, sortof. I found that for me, the best way to use the snorkel was to breathe out steadily through my nose, then take long breaths in from the snorkel. But those long breaths don't get you a lot of air, because the snorkel is narrow. And when doing flip turns, make sure you take a nice deep breath just before, so that when you come off the wall, you'll have enough lung power to blow out the water that filled the snorkel. You could also breathe out from the mouth while doing the flip turn, but I found that less effective than the blowout method.
So ultimately, the snorkels do two things - they help teach you to keep your body still, and they train your lungs a bit. This isn't the kind of tool I'd use for a whole workout - maybe a 3x300, or 2x400 with the snorkel is all you'd need to get a good taste of it. In the end, they aren't the easiest things to use, but I feel like anything to break up the monotony of a swim workout is worth it.