Island: Kalimantan

This famed island is known to the West as Borneo. It's the world's third-largest island and is actually divided up among Malaysia, Brunei, and Indonesia. The bulk of the 287,000 square miles, though, belongs to the Indonesian side and is called Kalimantan. It's also home to one of the world's richest rain forests.

Those best suited for a visit to this island are ecotourists and people who want to experience this incredible biodiversity before it's destroyed by loggers eager to harvest tropical woods. Kalimantan is less touristy than Malaysian Borneo (or Sarawak), so the traveling can be slower going, but the deep forests and the indigenous Dayak culture - famed for its communal longhouses - can make it well worth the journey. Having some basic ability in Bahasa Indonesia, the Malay-like national language spoken across the country (in addition to the local dialects), can be helpful in getting around.

Some tourists stick to East Kalimantan and its capital, Samarinda, where you can travel up the Mahakam River by longboat. But probably the most celebrated areas are the orangutan preserves started by legendary conservationist Biruté Galdikas, where you can still see the endangered species (whose name means "man of the forest").

"Visitors to Kalimantan usually go for the orangutans, and you can even stay in guesthouses near the research camps," says Meinarti Fauzie, a spokeswoman for the Indonesian Consulate in New York. She suggests flying to Palangkaraya, Central Kalimantan's capital, before you make the 120-mile trek to preserves like the 2,500-square-mile Tanjung Puting National Park, where Galdikas's renowned Camp Leakey is situated.

Islands: Flores, Sumbawa, and Komodo

Keep traveling along the chain that takes you from Bali to Lombok and you'll arrive at these three neighboring islands. First, you'll reach Sumbawa, where the remnants of an ancient sultanate, complete with teak-laden royal palaces, make you feel "as if you've stepped back in time," says Fauzie. There's also the volcanic Mount Tambora, whose eruption in 1815 wiped out the kingdom of the time and is said to have been larger than Krakatoa's.

Farther along is Flores, an island with a Catholic-influenced culture (thanks to its history as a Portuguese colony) and renowned for its Easter processions, a rarity in Muslim-dominated Indonesia. Combining those traditions with an unspoiled terrain that some liken to the Bali of decades ago, Flores makes for another unique stop on your itinerary.

Perhaps Flores's most memorable sight is Mount Kelimutu, a volcano in the island's central Ende region, with its three neighboring lakes that range in color from turquoise to reddish to dark brown. Another lure is the legendary Komodo Island, right on Flores's doorstep. The Komodo dragons can grow up to 10 feet long, can weigh as much as 200 pounds, and can eat six pounds of meat in a minute, so "you definitely want a guide," laughs Fodor's Kidder.

Travelers often opt for cruises that combine visits to all these islands rather than take them on one by one, which is more difficult. Travel in this region can be rustic, but you can recharge at the Amanwana resort on the nearby island of Moyo. The resort is made up of 20 air-conditioned, hardwood-floor tents in the middle of a rain forest; the getaway is part of the Amanresorts chain, so it's an ultra-luxe wilderness experience. The resort also offers a live-aboard cruise - seven days on a luxury boat that takes you through the local seas.