I have had sea lions (or seals I'm not actually sure how to tell from just the head poking up) come up near my boat and look curiously at me. I think they are just curious about what is this strange, noiseless thing going along... since most boaters are making a lot of noise with their engines.
I would certainly never intentionally approach them. Even an accidental bump could result in a very cold, wet spill.
Back when I lived in Northern California, I know it was necessary to stay clear of seals... the elephant seals only look clumsy on land. They can cover ground at a good clip, weigh a bunch and are territorial! I would expect sea lions to be the same.