I appreciate the previous reviews noting that the shoes run big.  This is accurate! I'm a 7.5 and I ordered a 6, they fit great.  If they were looser they would slip off in the water I think.  I don't know that this is a totally helpful review because I haven't actually used them in the water yet, but I'm taking them to hawaii in hopes that they'll keep my feet safe and be good for snorkeling and walking around the beach and tidal pool areas.  Maybe I will try to update and say how they did!