Northeast of Cruz Bay on St Johns, the snorkeling at Trunk Bay is popular with beginner snorkelers for its calm water and quarter mile wide scenic palm-lined beach. Trunk Bay has a marked snorkeling trail that is 675 feet long winding through 3 feet to 18 feet deep water along the west side of Trunk Bay Cay, which is the most interesting side. The Trunk Bay Underwater Trail has are 15 underwater plaques along the trail that explain the ecosystem and identify marine life in 5-15 feet deep water. While snorkeling in this bay of St Johns, it is common to see blue tang, yellowtail snapper, parrotfish and butterflyfish, along with octopus in the rocky shallows. In the middle of Trunk Bay, you may see see green turtles, stingrays and eagle rays where the water is 15-30 feet deep.
The highlight of the reef fringing the cliffs from the west end of Trunk leading to Jumbie Bay are the various sea fans, whips and plumes, and some brain corals. In deeper water, there are a few large live star coral heads. At the righthand eastern end, there begins a very shallow reef that continues to Windswept (semi-private beach). The choppy water conditions may dissuade you from venturing further, though stark skeletons of a once magnificent reef here (kept clean by schools of parrotfish) might be of interest on an introspective, historical level. The Underwater Trail is usually very busy from about 9:30am to 3:30pm, especially on St Thomas cruiseship days.
After completing the Trunk Bay snorkeling trail, experienced snorkelers can head out to the two rock formations located about 200 yards offshore where you might spot eels and lobsters near the rocky bases.
Also for experienced snorkelers, the rugged little island Trunk Cay is a short swim offshore. From the main beach, you will notice a spit that divides the bay and points directly at Trunk Cay is best explored by starting on the right side and snorkeling counterclockwise to circumnavigate.
Note: It is not recommended to feed the fish at Trunk Bay since it disrupts their normal life patterns, and they may become aggressive toward snorkelers. Also, Trunk Bay is known for its murky water and less marine life compared to other snorkeling dive sites on St Johns.
To reach the Trunk Bay snorkeling from Cruz Bay, head east along North Shore Road (Route 20) to Trunk Bay. There is limited parking for about 30 cars. The parking area experiences heavy taxi traffic as well.
To reach the snorkeling on St John by air, you will need to first fly into the island of St Thomas using Cyril E. King Airport (STT). Then, you will need to take a taxi to one of the two docks with ferries heading over to St John.
Note: When snorkeling off St Johns USVI, be aware of potentially dangerous marine life including lionfish and sea urchins. Also, the coral reefs are in distress so be careful not to walk on or touch the coral.
Overall, Trunk Bay is the 1st most popular snorkel dive spot of all 15 snorkeling dives in St John.