My family went swimming at Playa Mann a few years ago. We did have a sea lion charge at my husband on the beach, completely unprovoked. My husband had been standing, facing the other way, and wasn't even looking at the sea lion and didn't know it was coming up behind him. As I yelled to my husband to look out, the sea lion took a warning "bite" toward my husband's leg, coming very close! I am sure it would have landed the bite if it had wanted to, so I am pretty sure it was just a "warning," but it was fairly scary! Someone told us afterward that this sea lion was the "boss" of the beach and that he liked to assert his dominance and protect his territory. I am not saying not to go to the beach or to swim but just, yes, keep your distance and be aware of your surroundings. Remember who is boss!