A mere 2km in diameter, tiny Aka-jima (阿嘉島) makes up for in beauty what it lacks in size. Some of the best beaches in the Keramas and an extremely peaceful atmosphere mean it's easy to get stuck here for several days. There's also some great snorkelling and diving offshore.
If you keep your eyes open around dusk you might spot a Kerama deer (慶良間シカ), descendants of deer that were brought by the Satsuma from Kagoshima when they conquered the Ryūkyūs in 1609. The deer are smaller and darker than their mainland cousins, and have been designated a National Treasure.