I remember swimming in the Galapagos about 500 feet from the beach and a shark swam underneath me, real slow, it didn't pay any attention to me and I wasn't bothered, but freaked me out how it just vanished.
Same holiday swimming in a sea filled volcano, walls vertical and dark deep water, looking for a colony of hammer heads was a bit spooky and felt quite vulnerable, was in a group but couldn't get out the water if you were attacked.
Same holiday again, was watching sealine bulls patrol the beach, swimming backwards and forwards, they both came out the water and I was told it was safe to swim so jumped in and the bloody bulls weren't happy and entered the water. They kept barking at me and prevented me returning to the beach so I swam about a 1/4 mile out to sea to where the ribs were parked. It was quite tidal and sloppy. I needed a hand to get out the water, I only realized how tired I was when trying to climb up the transom which surprised me because I used to run quite a bit. I then just lay down in the rib exhausted thinking: fuck swimming back. I don't know if they would have attacked me if I turned round back to the beach but it didn't seem a wise move.