There's frequent service from St. Thomas to St. John and Tortola, and less frequent service to Virgin Gorda and Jost Van Dyke. Virgin Islands ferry schedules are published on the website of the Virgin Islands Vacation Guide & Community. There's also a ferry from Charlotte Amalie's waterfront to the Marriott Frenchman's Reef Hotel. In St. Thomas, ferries leave from both Charlotte Amalie and Red Hook. Remember that a passport is now required to travel between the USVI and BVI by ferry. Schedules change, so you should confirm current schedules with the ferry companies.
Virgin Islands Vacation Information. www.vinow.com.