Re: Going to BVI! Bring cash?
Check your cards. I think Discover, Capital One, and Amex all currently offer at least some cards with no penalty for foreign exchange, they will convert every transaction at the official rate at the end of day (check on whether it is eod or end of cycle). If there are no penalties for foreign currency, and you aren't already a customer, tell them you've got a trip, a deadline, and if they can expedite things you'll open an account. And make sure that if it needs a different PIN, etc. to be used there, that they take care of that as well. (Sometimes you "must" have a 4-digit pin, sometimes 6, ask ahead.)
Cash is always good but plastic often safer.