Ask HN: Best beach to work for a week?

I'm leaving my job in August and have been working night and weekends on a prototype for a few months now. I know I'm going to be busy starting a company after I quit, so I'd like to take a week to sit on a beach and code, swim, repeat.

So I'm looking for suggestions on where to go. Anywhere in the world is fine. I just need wifi, sand, and water.

(Or, if you want to tell me what else I should be doing instead, I'm open to that...)