I'll put in my plug for wool socks again. Wool wicks moisture (sweat) away from yer feet, cotton holds it there. Basically, dry feet are comfortable feet while damp feet make a better place for bacteria and other small things to grow. Further, you're less likely to have yer shoe rub against yer foot if a dry foot is inside a wool sock: cotton gets damp and sticks and transfers the friction through to yer foot. Cool-max is an attempt to create a synthetic wool in order to get all of the benefits without the use of sheep.

So I'll always go with wool even in the heat.

Best

AA