I’ve heard of people creating treasure maps for their kids to follow while they are chartering. I think that’s an awesome idea.
If you aren’t quite up to creating your own treasure map, you can use the tourist version for the USVI at Island Treasure Maps. You can download the maps for St John and St Thomas from their website or pick up a copy at the airport in the Hotel and Tourism Association booth. While they look like they are obviously funded by advertisements, it’s still a fun way to explore the land side of the island!