Just the right thickness, it is not meant to be a wetsuit, but more like a stretchy thick T-shirt material. I wear an xl regular shirt and this is a little tight but does seem to pull in and support the extra er...large abs I have. Body Glove makes a great product and plan to use this snorkeling.Sizing is small. Order 1 size up.I bought the XL size of this, I'm 6'4 250lbs. I know i I have a long torso & was surprised that shirt actually compensated for that in length rather than width like most shirts do. Very satisfiedSeemed okay, running small. Returned because it came dirty with stains. Not good. :(paper thin material , don't think it will last more than 3 washesPOOR QUALITY! Don’t buy.