Trunk Bay Underwater Snorkel Trail, St. John

Trunk Bay is probably the most photographed beach in the US Virgin Islands. The crescent of white sand, the shallow turquoise water, and the green hills running down to the shore have appeared in travel magazines so often they've become a kind of shorthand for "Caribbean." But the real reason serious travelers seek it out isn't the view from the beach — it's the view from under the water.

The Trunk Bay underwater snorkel trail runs through the reef at the west end of the bay, with numbered underwater signs identifying the coral species and marine life at each station. It's a self-guided experience that takes about 20-30 minutes to complete, in water mostly 5 to 15 feet deep. Equipment is available for rent at the beach.

The Trail

The trail loops roughly 225 yards through the reef, starting and ending near the lifeguard stand. Signs are mounted on the reef bed — waterproofed and secured to prevent damage — with short descriptions of what you're looking at. You'll encounter brain coral, elkhorn coral, sea fans, and the usual cast of Caribbean reef fish: sergeant majors, parrotfish, blue tang, French angelfish, and if you look carefully under ledges, the occasional hawksbill turtle resting in the shade.

The labeled-trail format is especially useful for first-time snorkelers who wouldn't otherwise know what they're seeing. The numbered stations give you something to follow, which keeps the experience organized without the need for a guide. Snorkel instructors have noted that the concrete identification practice makes visitors more observant of the reef structure than free-exploration snorkeling does.

The Beach

Outside the trail, the rest of Trunk Bay rewards exploration. The far east end of the beach gets considerably fewer visitors than the main area — the sand narrows there but the water is clear and calm. The bay is sheltered from the north and east by a headland, so swell rarely penetrates to the shore. The combination of calm water, a sandy bottom, and lifeguards on duty makes it one of the most accessible snorkel beaches in the territory for swimmers of any level.

Facilities at Trunk Bay include changing rooms, showers, restrooms, a snack concession, and a small gift shop. A picnic area sits under trees above the sand.

Crowds and Timing

Trunk Bay fills up fast. Day-trip boats from St. Thomas arrive throughout the morning, and the beach is busiest between roughly 10 a.m. and 2 p.m. Arriving when the gates open — or booking a tour that gets you there first — makes a substantial difference. By mid-afternoon the crowds thin as boats head back, and the last hour before closing is often the most peaceful.