No Passport Required
Puerto Rico, Vieques and Culebra are US Territories therefore, you do not need a passport if you are travelling from within the US. If you are travelling to any other Carribean destination you may need a passport and should check with your local US embassy.
No Adapter Required
If you are travelling from the US and have standard electronics with you, there is no need for an adapter. 110 Volts, A.C., is the standard voltage in Vieques, as in the United States. Regular American Type plugs.
Rent a car well in advance
Be sure to reserve a car well in advance. Vieques is a small island and rental car availibility is limited. There are many isolated and secluded beaches that you will want to visit that can only be reached by automobile, preferably a 4-wheel drive as many of the roads to the beachs are unpaved, filled with holes and bumpy!
Do It in The Dark
The Bioluminescent Bay is a truly amazing, unique experience, best seen during dark nights. For the best viewing conditions plan your trip to Vieques when there is very little, to NO MOON in the sky.