I agree with Charles 100% on herb (I was joking about the puna butter) local PD and DUI.
Although I presume you are too smart to try to score weed off a stranger, drive drunk, or speed in a unknown area.
If any tourist tried to score weed you would most likely be buying from a police officer (bad) or a junkie/crack head (worse).
When I am there I can't resist going for a swim first thing in the morning when I wake up and one last splash before the sun goes down. Perhaps I have not been nibbled on because I stick to the shallows... or maybe the sharks are on a low cholesterol diet.