Members of the Dolphin Club & South End Rowing Club swim and co-exist happily with the seals and sea lions in the waters of the San Francisco Bay. Give them the space they deserve and they rarely are cause for much concern. Fairly frightening when you see one pop his head up close to where you're swimming, but it's not dangerous.

The biggest danger to swimmers has been, is, and will likely always be boats, especially ones with propellers.