St. Croix is roughly 28 miles long and 7 miles wide — too large to explore without transport. Like the rest of the US Virgin Islands, driving is on the left (a legacy of when these were Danish colonies and before American cars arrived). Rental cars are widely available at the airport and in Christiansted, and a car is really the only practical way to reach the western end of the island and the beaches outside town.
The island's two main towns, Christiansted in the east and Frederiksted in the west, are connected by a relatively straightforward 28-mile drive along Route 70 (Centerline Road). Taxis are readily available in Christiansted; negotiate the fare before you get in. Shared safari buses — open-air trucks with bench seating — run along the main road between the two towns and are the local's transport of choice.