Speaking of which, there's reportedly a resident 7-gill shark that hangs out off of Santa Cruz/Santa Rosa Islands in the Channels. Personally, I've never seen it, but people on some of my bug dives have.
Apparently, the shark has learned that if it bumps divers, they'll often drop their game bags. Free meal time. Usually happens at night.
I've never been bumped by a sea lion while diving, but quite often get the harbor seal "tug the fins" game going. Also found out that if you roll onto your back and settle on the bottom, then wave your fin tips back and forth, the seals will often come up and scratch their bellies (along with the most ecstatic look you could imagine on their faces...) Cool stuff. At least until the fin tugging gets annoying.