St. John [1] is shaped like a paint splotch. Cruz Bay [2], on the far western end of the island, is where ferries and boats from neighboring islands arrive. Many of the best and most popular beaches are along the north coast of the island, accessible by scenic North Shore Road (Route 20). Coral Bay [3] is a sprawling settlement along a wide, horseshoe-shaped bay on the far eastern end of the island. Centerline Road (Route 10) connects Cruz Bay and Coral Bay.
From Coral Bay you can drive to the remote eastern tip of the island on the East End Road (Route 10) or head south through remote seaside communities and luxury villas on Salt Pond Road (Route 107). Both drives take you to remote beaches with good snorkeling and few crowds.
Links:
[1] http://www.moon.com/destinations/virgin-islands/st-john
[2] http://www.moon.com/destinations/virgin-islands/st-john/sights/cruz-bay
[3] http://www.moon.com/destinations/virgin-islands/st-john/sights/coral-bay