Although it’s just 20km west of Ishigaki-jima, Iriomote-jima could easily qualify as Japan’s last frontier. Dense jungles and mangrove forest blanket more than 90% of the island, and are home to a variety of exotic wildlife including the rare yamaneko, a nocturnal and rarely seen wildcat.
Needless to say, Iriomote-jima is the perfect destination for outdoor enthusiasts. The island’s rugged cross-island trail is one of the most rewarding (and difficult) treks in the Nansei-shotō - if you're thinking of tackling it, be aware that you need permission from the police first, who do not let trekkers go it alone. The island is also criss-crossed by a series of muddy rivers (which wouldn’t look at all out of place in the Amazon). They’re easily explored by river boat or kayak. Add to the mix sun-drenched beaches and spectacular diving, and it’s easy to see why Iriomote-jima is one of the most popular destinations in the Nansei-shotō for domestic travellers.
In true Japanese fashion, Iriomote-jima plays host to countless day-trippers from Ishigaki-jima, though few people stay on the island long enough to fully appreciate its charms. Although half a day is enough time for a quick river trip, two or three nights on the island will give you enough time to fully explore one of the least-developed corners of the country.