There are glacier fed lakes when i live. You can float in incredibly cold water and if you have just the right equilibrium you can half float in freezing cold water while half getting a nice sun bath. And it IS very weird.

One spot I camped at for many years had nice sandy area that was about 200 meters out into the lake before a drop off. As it was only about a meter deep it used to warm up the top foot or so of the water when it was fairly still and you could stick your arm down into the water and actually feel the temperature drop like there was a line underneath the water.

Was great place to camp before it got overwhelmed by mosquitos