[mikejarema]

I regularly do cold water swims in spring and fall months, and wholeheartedly agree with the amazing feeling after a good 10-20 minute dip.

I find the first few minutes of the swim are the hardest, as your body is adjusting to the cold, surface blood vessels are constricting, etc. The next 5-15 minutes are fantastic! I don't usually push it much beyond that.

But any discussion of the benefits of cold water swimming also needs to highlight the risk. If you're thinking of trying it out, make sure you're acutely aware of the temperatures you're dealing with, how long you're planning on being in the water, and that you understand the body's reflexes to cold water submersion. Here's a good resource covering these points: http://seagrant.umn.edu/coastal_communities/hypothermia

[danenania]

Very good point on the risks. I recommend immediately running, biking, or doing something else to warm your body up after getting out, especially if it's not a hot day. It only takes a couple minutes of running to warm up again, but if you stay still you can be shivering for an hour after.

I've also noticed that there are a few phases you go through. First there's the initial shock--that lasts a few minutes as you say. Then you adapt and it starts feeling good. But if you stay in for long enough, you can start feeling cold again in a deeper more full-body way that indicates your overall body temperature is decreasing. That's when you want to get out :)