Frederiksted Beach, also known as Fort Frederik Beach, is located in the town of Frederiksted just north of the Pier and Fort Frederik (across the street from the ballpark).  It is the most easily accessible beach from the cruise ship pier. An easy stroll around the front of the fort puts you on Frederiksted Beach. There are some trees here that provide relief from the sun, and the park across the street is a great spot for young kids to play. With public restrooms, picnic tables, and plenty of space to spread out, you could easily spend the entire day here, relax, and then watch sunset.  
The northern end of this beach offers every amenity you could ask for – a restaurant and bay, a board shop with rentals and lessons, chair and umbrella rentals. You may also want to try your hand at fishing at this beach. Frederiksted Beach can be rocky in places, but there are places to enter to swim – just watch out below for sea urchins!  This beach has calm water, making this a area for paddle boarding, swimming and snorkeling.  Make sure to keep a look out in the clear, shallow water for octopus, flounder, butterfly fish, angel fish and blue tangs.