There are plenty which don't swim if they can avoid it, but I too can't think of any which actually can't swim.
No -- I just have thought of one! Humans, if not taught. Apparently small babies can swim instinctively, but I never had the nerve to try it with my two.
It would make sense if gorillas were like us in that respect. I know that they may not get the idea of sex unless they have seen it -- and they are sometimes shown "gorilla porn" to help.
I think orangutans do swim. I don't know about chimps or bonobos.
Bats can swim. The gorillas can't swim because of the weight and shape of their chests. If you think about their body it could not float on its front and keep it's head above the water.
Laura-sakura's right, Boyo -- bats swim quite well if they have to. Also some other surprising mammals swim well, such as moles.
Does anyone know about gorillas for sure, or is that another myth?
I'm sure they could learn, if we can -- they could swim on their backs, for a start.