On the southeastern tip of St Croix USVI, the snorkeling at Isaacs Bay is known to be one of the best dive sites on the island. There are coral reefs with over 400 species of fish, including four-eyed butterfly fish, blue tangs and parrott fish.
Isaacs Bay is part of the St Croix East End Marine Park. The East End Marine Park was setup in 2003 to protect over 60 square miles of marine habitat enclosing the eastern tip of St Croix. Since the marine reserver is a no-take zone that protects fish and lobsters, there is amazing snorkeling with plentiful marine life.
To reach the Isaacs Bay snorkeling on St Croix from Christiansted, head east to Point Udall. Just before the Millennium Monument, follow the steep trail south for about 20 minutes down to the beach at Isaacs Bay.
Note: watch out for rip tides at this secluded beach.
Here are some general notes about traveling around St Croix. First, if you plan to be snorkeling at multiple dive sites on St Croix, you will want to have a rental car so that you are not at the mercy of the St Croix Taxi Association. Those taxi costs, especially for multiple people, add up quickly. When renting a car, you will want to make your rental car reservation several months in advance to make sure there is actually one available when you arrive. Multiple reservations might not be a bad idea, but just make sure to cancel the extra reservation when you actually get your car. There several popular island-only rental car companies, too. Second, do not leave your valuables unattended anywhere due to theft on the island. The hotel safes are known not to be all that safe, either. Carry valuables with you or leave with someone you trust. Third, make sure to arrive on island with low expectations for the beach resorts, especially, the Carambola Beach Resort and the Chenay Bay Beach Resort. Check out the hotel review websites and make your own educated decision.
Overall, Isaacs Bay is the 6th most popular snorkel dive spot of all 10 snorkeling dives in St Croix.