Okinawa's coastline ranges from busy resort beaches with full facilities to remote coves you will have entirely to yourself. The west coast generally has calmer water and better sunsets, while the east coast faces the Pacific and can be rougher. Water temperatures stay swimmable from April through October, and many beaches have nets to protect against jellyfish in summer.
The resort beaches in the central-west area around Chatan and Onna are well maintained with showers, rental gear, and lifeguards. Further north, beaches become quieter and more rugged -- coral shelves, tide pools, and stretches of white sand backed by jungle. Some of the best require a vehicle with decent clearance to reach, but the effort is rewarded.