I really wanted to love this hat. It does keep moisture out with the taped seams and all. However, due to the nature of the materials and construction, it doesn't breath very well in my opinion; especially if you will be doing any kind of strenuous activity and sweating. After a few hours into a mountain run, it completely sweated out from the inside and nothing but dried salty sweat caked on the outside. This is more of a cool weather hat best used for cool Spring/Fall rainy days where you won't be sweating.
Jim the Ultrarunner