More than likely you are suffering from low potassium, which causes cramps in muscle groups that are being stressed, I.e. Toes and arches while swimming. There are plenty of sources for potassium, you could get 200mg (not much) from a banana, 2200mg from a cup of peppermint tea, or simply use a tsp of salt substitute (potassium chloride) in a big glass of water once every ten days or so and never get cramps again! Be forewarned- it tastes like drinking sweat.... But within 45 minutes, you will no longer be experiencing cramps. Oftentimes low potassium is the culprit for heart episodes as well, so if you sweat a lot, take your potassium!! V8 juice is pretty good, too.
There are several possible causes. Muscle strain is one. Being on your feet a long time, weak arches, high heels,etc. Go stand in the tub and let hot water run over your foot and fill tub till it relaxes. You have to pull the toe in the opposite direction from the spasm to release it. Low potassium is another reason. See the above. eating a banana a day is good prevention. Sometimes it is insufficient calcium in your diet also. 3 glasses of milk a day. Diuretics in blood pressure medicine is another culprit. They leach potassium from your body. a hot pack or heating pad is another way to relieve theis cramp. If it persists, I would tell the dr b/c you may have another condition that needs to be addressed.
Eat more bananas and eat more salt.
I don't believe any of these answers. I can make toes cramp just by holding my foot at a certain angle. It must have something to do with leg muscles pulling on them, because you can see the metatarsals come to the surface at the same time. Something is pulling on them, and it's more than likely some muscle stiffness in the lower leg.
For some reason I got cramp in my toes when I got in the bath, I found the cold tiled floor fixed better whilst bending the toes back.