You can catch the Charlotte Amalie ferry and take it over to St. John. This ferry is in downtown STT and takes longer to get to STJ, vs taking a cab all of the way to Red Hook and then a much short ferry to STJ.
The National Park Service offers a hike to the Petroglyphs and then a small boat ride back to Cruz Bay. This is a nice day.
Or, once you land in Cruz Bay you can take a hike to Honeymoon Beach. Stop on the way and pick up a sandwich and drinks and spend the day at a Beautiful beach.
and, while there, Best to also stop at St. John Spice Company at the Cruz Bay dock before catching the ferry back to STT, and buy some Nice hand mixed spices. Ruth and Ron also have teas and coffee, sauces, jams, pepper relishes, and other island flavored and favored items. Not to be missed!!
Enjoy!!
Oooooooops!!! The above is for St. John USVI and not St. Johns in the BVI.