I will admit my concern with getting these was based on previous, other brands' waterproof socks...they wouldn't fit properly, the heel would bunch up, my feet would get swampy. I am very happy to report I've been wearing these for two weeks for hiking, trail running, walks around the neighborhood here in Winter in Northcentral Pennsylvania, so mid-20s in temps, a mix of snow, ice, and rain weather and they've worked really, really well! No bunching up, my feet feel warm and dry, very comfortable. They don't slide during activities. After a number of hours I have noticed my feet sweating a bit but to date, there's nothing out there that can be 100% waterproof and breathable for extended periods of time. I love these socks and very happy with them!