What are the best day trips from St. Thomas?

St. John over everything else for a single day. The Red Hook ferry departs hourly from 6:30 a.m., costs $7 each way, and drops you at Cruz Bay in 20 minutes. One of you wants to hike the Reef Bay Trail, 3.6 km downhill through dry forest with Taino petroglyphs carved into streambed boulders halfway down. The other wants to lie at Gibney Beach. Both work from Cruz Bay. Trunk Bay charges $5 per person and has an underwater snorkel trail marked with plaques on the sea floor, but it fills with cruise-ship groups by 11 a.m. The Virgin Islands Coral Reef National Monument, established in 2001, protects underwater terrain off St. John's south shore, and snorkeling near Lameshur Bay tends to stay quieter all day. The Catherineberg Sugar Mill Ruins sit on Centerline Road about 3 km east of Cruz Bay. Coral-stone walls still hold their shape after two centuries. You might catch the smell of bay rum trees along the trail if the wind is right. The last ferry from Cruz Bay leaves around 11 p.m., so dinner back on St. Thomas is still on the table.

Water Island is the answer when one partner wants adventure and the other wants a hammock. The ferry leaves Crown Bay Marina every hour, takes 10 minutes, and costs $10 round trip. Honeymoon Beach sits on the western shore, about a 15-minute walk from the dock on a packed-dirt trail through scrubby bush. The sand is coarse and golden, the water is warm enough that getting in feels like nothing at all, and the beach bar (when it's open, which is most days but not all) serves frozen painkillers in plastic cups. The whole island has fewer than 200 residents. You'll hear tree frogs and generator hum, not DJ sets. Fort Segarra, an unfinished World War II submarine base cut into the hillside, is a 20-minute walk south from the beach. The tunnels are concrete, unlit, and cool in a way that feels 10 degrees below the humidity outside. Bring a phone flashlight. This is the day trip for couples who had an overcommitted morning and need to slow down by 2 p.m.

The British Virgin Islands are close enough to see from St. Thomas, but crossing means a passport and a $40-75 customs fee depending on which island you clear into. Jost Van Dyke is 32 km northwest, reachable by charter or organized boat tour (typically $150-175 per person, departing from Red Hook or Crown Bay around 8:30 a.m.). The draw is the Soggy Dollar Bar at White Bay, where you swim to shore because there's no dock. The water is shin-deep and warm, the sand squeaks underfoot, and the painkiller cocktail runs $14. It gets loud after noon when the catamarans arrive. Tortola is the bigger BVI option, 45 minutes by ferry from Red Hook ($55-70 round trip, passport required). Cane Garden Bay on the north shore has calmer water than most St. Thomas beaches and a string of beach bars playing soca at a volume that still lets you talk. Mind you, both BVI trips eat 2-3 hours in transit and customs processing. If your day together is already short, St. John is the honest pick.

St. Croix sits 64 km south and needs either a seaplane (25 minutes from Charlotte Amalie harbor, roughly $100-180 each way depending on season) or the inter-island ferry (90 minutes, $50-90 round trip, the schedule changes frequently so confirm times the week of). The seaplane ride itself is worth the fare. You'll fly at about 300 meters over water that shifts from green to deep blue, and the vibration of the prop fills the cabin. Christiansted's boardwalk on King Street has better restaurant density than Charlotte Amalie, with less cruise-ship traffic. On a quiet weekday afternoon you can sit with your feet near the water, salt breeze off the harbor, plates of conch fritters on the table. Buck Island Reef National Monument, 2.4 km offshore from Christiansted, has a marked underwater snorkel trail through elkhorn coral. Half-day boat charters run $60-85 per person. To be fair, St. Croix is borderline as a day trip. The seaplane schedule and ferry reliability both work against you. Couples who want a real day on St. Croix might be better served by an overnight at a Christiansted guesthouse.