When I was about thirteen years old I tried to get close to a large bull in my 7 ft duckboat in open water on Richardson's Bay. He kept swimming away but whenever I saw him surface I would pursue. After a while the sea lion tired of this little game and he surfaced near me roaring loudly while giving a look that needed no interpretation. I stopped intentionally harassing sea lions at that moment. My little boat felt extra small and it was a long way back to shore. In the 1970's I was chased by a sea lion when I motored close to rocky Pt. Blunt on Angel Island one afternoon in the early 1970's. I was going along about 10-12 kts in a small aluminum boat when the sea lion appeared alongside barking and giving me the stink eye while jumping out of the water on a parallel course but angling closer with each leap. I was frightened and got out of there quick. When I trolled for salmon commercially in the mid-70's a lot of commercial fishermen shot at sea lions. Sea lions would follow trollers stealing what ever they caught. Sea lions that have been injured by fishermen, or that have seen friends, lovers, or relatives injured or killed by fishermen might not appreciate being approached by humans. They can also be very territorial, especially when mating. I was a sea urchin harvester from the late 70's until the early 90's and I never heard of sea lions causing a problem for divers in California however some divers working out of Port Orford Oregon reported being bitten on the head by male sea lions. Evidently this is some form of sea lion domination display. The divers reported that the sea lions put their mouth over the top of the divers head biting down hard enough to cause pain while roaring and blowing stinky hot breath. Understandably, this scared the s**t out of the divers who experience this. This happened on a particular reef when the sea lions were breeding. Some divers were bit harder than others but none (that I heard of) suffered serious injury. A problems I experienced at Fort Bragg one year in the 1980's was when several large sea lions include big bulls decided to make a home for themselves on our dock and they refused to let us pass to get to our boat. We tried spraying them with water from a hose but they seemed to enjoy that. A hand held air-horn seemed to work just fine. They respect a creature that can bark louder than they can. PS Although it was a common practice at the time, I never shot at sea lions. I stopped fishing in the mid-90's. The only thing I shoot is a camera.