+1 for courchsurfing.com. I've used it on five continents with great success, and hosted some awesome folks. You can't be picky, though. Or particularly concerned with your privacy. There are several dive related groups on CS, so you may want to check there.
It's generally polite to give some advance notice as people in desirable destinations during busy times tend to be swamped with messages like "Oh no, I'm in town with nowhere to stay! Can I stay at yours?"
It's generally polite to give some advance notice as people in desirable destinations during busy times tend to be swamped with messages like "Oh no, I'm in town with nowhere to stay! Can I stay at yours?"