Foot cramps while swimming

Suffer from this too!  Usually after wearing fins where my foot is in an unnatural position, if I swim through it eventually it shoots up to my calf.

Kick drills and backstroke were recommended to me - increases flexibility in foot/ankle.  Like you I try and hydrate etc and have now started taking magnesium supplements, figure it can't hurt!

I use to get these all the time as a high school swimmer. It brings back memories of me in the middle of the pool, holding my foot, while my coach screamed at me  

I think it is related to fatigue, as I would always get them at the end of our 2 hr workouts. I also agree with the above poster that I think it is related to pushing off the wall too hard since I would always get them off the wall. 

I haven't gotten one recently but I don't swim as long and I drink way more water throughout the day now than I did as a high schooler. When you get it, try focusing on relaxing your foot - same if you get a charlie horse - focus on relaxing your calf.

Also maybe try rolling your foot at night with a golf or tennis ball to relieve some of that tension.

As a relatively new swimmer (past year), I started getting these cramps once I figured out my foot needed to be pointed and not flexed (yeah, I was that bad).  My calves would seize up midway through my swim sets.  If your ankles and lower calves are inflexible, it's actually pretty hard to relax in a toe-pointed position.  It takes some muscle to force your foot into that position. At least it did for me.  It's somewhat unnatural for new swimmers.

I've been stretching my feet and lower calves (due to plantar fasciitis as well) more frequently and have noticed some increased flexibility while swimming.  With the increased flexibility and maybe more experience, I'm having fewer, if any, cramps.

Just keep swimming and stretching and maybe work in more kick sets.  I bet the cramps begin to let up.

That's good advice Shane. 

I usually only have this late in my workout when I'm overdoing my kick to make up for tired arms.  In the last ocean 5K I did, I was cramping from 3 km in to the end. 

I believe one of the benefits of training with flippers is that it does limber-up your ankles so that they're more loose in the water when you're swimming.