That's why you don't wear fins when you swim! lol.

Anyway, this is fairly common because you're swimming with fins. It's quite easy to cramp in the water especially if you're "giving it your all."

The trick abotu swimming is technique rather than muscle power. It's quite easy to do the wrong technique and tire yourself easy.

Usually with fins I do side strokes back and fort the pool. I used to get the cramps like you described. What I found out is that I gave too much effort. Just relax and swim without tiring yourself out.

If you ever go in a lake or ocean, be sure to wear a life vest in case this happens out in the middle.

If you really want to swim with fins, then you might want to get better fins. The duck feet are probably the best for surface swims and general snorkeling. It adds floatation while being easy on your legs. For diving, the rocket fins are the best, but they are tough on your legs.

The best way to go with fins is to use the paddle board and swim every day for two hours with them on. You'll never cramp out again.

It's not required that we swim with fins. The teacher just wanted to start us out with them so we didn't tire so easily. I've been swimming without them and it feels much better. No more cramps. She's slowly transitioning us into swimming without them, she'll have the class wear them for the first half and then take them off for the second half of class. I just haven't been wearing them at all, it makes for a better workout that way.