These tights are perfect as Sun coverage and slight extra warmth for either tropical snorkeling, or for summer in cold mountain lake water (looking at you Lake Tahoe!). They are super-stretchy. They fit true to size, and are stretchy enough (especially when wet) that if you are between sizes, I’d actually go down to the smaller size. I only wish they came in petite length (then they’d truly be perfect!). They were long on me (I’m 5’4”) and bunched a little behind the knees. If you’re expecting wetsuit material, these are NOT that (which is good or bad depending on your needs). The warmth provided is literally just a little extra, but it’s great for those in between conditions where you don’t really need a 2-3 mm wetsuit, but you want a little extra.