Emphasis mine: "Sometimes if you run into em, and they're a little bit aggressive and you"re trying to get some work done, then you, you try and swim at em, and sometimes it'll spook em away where they don't come back, and sometimes they'll loop back around from behind and then they'll come back and check you out again." So says Ron Elliott, a sea urchin diver in the Farallons, in the documentary above.
Apparently he also considered becoming a North Australian river-swimmer, or an African-savannah run-around-naked-smearing-meat-on-yourself-and-shouting-"EAT ME" guy.
I have trouble concentrating on work if someone is talking nearby. Great whites circling would be at a different level I think.