Anyway...I honestly couldn't say. I don't surf, I only swim, and I've never gone swimming with mine. Other than that, I don't think I've noticed anything weird about how they handle sweat or moisture compared to other shoes...they get wet when you're wearing them somewhere wet, although I find myself sweating less on my feet with these because I'm not wearing socks with them (although you can wear toe socks) and they don't smell yet (they're only about a month old). The upside is tossing them into the washer to clean them.

I have the sprint version though, vibram makes a "flow" version made of neoprene that might be more appealing to you if you surf.