I went to the Revillagigedos on the Solmar V; we saw dolphins at Roca Partida, the only time I've ever seen them u/w. I also set my personal depth record of 146 feet -- on accident, whoops. Well, we'd meant to go to 120-ish, so I wasn't *that* off, but still. And that was also the only place I've seen hammerheads and galapagos sharks. It was a very intimidating day! Just the day before we'd been at the boiler, with the gangs of mantas. That was quite a trip for big stuff.
Actually the shot for my avatar was taken at Roca Partida. There was an enormous school of some smallish jack (bigeye?), something like a million, just astounding. This brought in the bigger jacks, who were aggressively hunting in the school, and sharks...
One of the DM's carried a billy stick that whole day, though we didn't get any close encounters I have heard that it pays to be wary of the silkies.
From what I've seen the Sea of Cortez is a lot more fished out, frankly I'm more worried about bozo boat drivers than aggressive sharks, but I'll keep an eye out!
Hmmph, I probably should post this in the fish-stories section of the boards...