A boat day is the thing guests talk about for years afterward, and it is also the single biggest line item most people add to a St. Thomas trip. The confusing part is that "booking a boat" means four different products at four different prices, and the websites all use the same photographs. Here's how the options actually differ.
The shared catamaran day sail
The default, and for most first-timers the right call. You buy seats on a boat that already has a route: a few hours of sailing, two or three snorkel stops, lunch and an open bar included, back by late afternoon. Budget roughly $125–200 per person for a full day.
You're on someone else's schedule with twenty strangers, which is the trade. What you get is a captain who knows where the water is clear today, zero logistics, and the version of this day that's hardest to get wrong.
The sunset sail
Two to three hours, usually $75–125 a head, cocktails and something to eat, back at the dock in the dark. It's the cheapest way onto a boat here and an easy add-on to a week rather than a whole day surrendered. If you've only got one evening to spend well, this competes honestly with a nice dinner.
Renting the boat yourself
A powerboat for the day runs in the range of $400–800, split across your group. You choose the route — Water Island, the cays off the east end, a run over to St. John — and you stop where you like for as long as you like.
This is the best value on the list if, and only if, someone in your party is genuinely comfortable driving a boat in open water with current and other traffic. Be honest about that. "I've driven a pontoon on a lake" is not the same qualification.
The private charter
Captain, crew, your route, your day: roughly $800–2000 depending on the boat and the length of the trip, which lands somewhere around $130–330 per person once a real group splits it. For six or eight people it stops looking extravagant fairly quickly, and for a milestone trip — a big birthday, a family reunion — it's the day everyone remembers.
Boats go out of Sapphire Marina, which is a short walk from our condo at Sapphire Beach and about twelve minutes down the hill from Mahogany Seaview. Guests at either place have done a 9am departure without an alarm-clock crisis.
What nobody tells you
Book the morning slot. The water is flattest early and the trade winds build through the afternoon. A 9am departure and a 2pm one on the same boat can be two different experiences.
Check the wind, not the rain forecast. A passing squall costs you fifteen minutes. Fifteen knots of wind costs you the snorkeling. If the operator offers to move you a day, that's usually good advice rather than a sales tactic.
Bring more water and shade than you think. Six hours of reflected sun off the water is not six hours on a beach. Rash guards beat reapplying sunscreen on a moving boat.
Have cash for the crew. Tips are the crew's income, and cards on a boat are a hassle for everyone.
Confirm what's included. Some rates cover park fees and fuel; some don't. Ask before you book, not at the dock.
The cheap version that still counts
If the budget says no to all of the above, the ferry from Red Hook to Cruz Bay is about $8 each way and twenty minutes on open water with the islands going by — and it's how we get to St. John for a beach day. The Water Island ferry from Crown Bay is closer to $5–10 round trip. Neither is a charter. Both put you on the water, and on an island this size that's most of the point.
Open weeks and current discounts at both of our places are on the deals page.