Members of a peace group \Members of a peace group "Paddle For Peace" dip to the sea under sunset at Kuta beach. (Firdia Lisnawati)

At Kuta Beach in Bali, hundreds of Australians swarm in and out of beachside pubs. At Angkor Wat, a jovial group of 50 South Koreans follow their guide up a narrow stone staircase, blocking the way as Granny slowly takes the last few steps. In Bangkok, it's an elbow-jabbing scrum around the Emerald Buddha at the National Palace as tourists from dozens of nations jostle for the perfect photo op.

As Southeast Asian tourism heats up, it's harder than ever to find breathing room at the most popular destinations. The annual number of non-stop flights from the U.S. to Asia has almost tripled in the past ten years, and even once-fringe destinations like Vietnam and Cambodia are now regular stops on the well-beaten Southeast Asian travel path. And with tens of millions of newly minted middle-class Chinese citizens gearing up to see the world, things are only going to get more crowded.

Where can you experience authentic Southeast Asia without sharing it with busloads of other travelers?

The answer is simple: Find the places that fewer people know about. Throughout Southeast Asia, it's easy to find viable alternatives to the wonderful but overcrowded destinations to which throngs of travelers typically flock. It may require an extra flight or an extra day, but you'll be rewarded with an experience that will give you a fresh perspective on the region that you might not get at the more obvious tourist stops.

Perhaps the best example is Lombok, the Indonesian island located directly to the east of its much better known neighbor, Bali. About 131,000 Americans visit Indonesia every year, and the vast majority of them head straight to Bali, leaving the rest of vast Indonesia unexplored. Lombok is a less-manicured, less bustling Bali, with all the culture, food and scenery that make Bali an ideal vacation destination—only without the crowds. And, it's accessible via non-stop flights from several Asian hubs. Luxury resorts have been slow to arrive on the island, but they're popping up now. The best thus far is the small, ultra-luxurious Tugu Lombok, tucked away on the secluded Sire Beach on the island's northwest coast.

In Thailand, legions head for the beaches of Phuket and the popular islands such as Koh Phi Phi and Koh Samui. Far fewer in-the-know travelers save time by staying much closer to Bangkok on the ritzy beaches of Hua Hin, beaches that are good enough for the Thai royal family and therefore good enough for you. Other savvy sun worshipers skip Thailand altogether, and head instead for relatively inexpensive Malaysia, which receives just one-third the number of American tourists as Thailand. On the 99 small islands of the Langkawi archipelago, not far from the Thai border, you can set up camp at any of a dozen world-class resorts — many are priced at under $200 per night. Then explore the beaches, fiercely protected nature reserves, rain forests and mangrove swamps.

Offbeat adventures in Malaysia

"Malaysia is truly a multi-cultural destination," says Mary M. Scully, marketing director for Tourism Malaysia. "Its population is a mix primarily made up of ethnic Malays, Chinese and Indians, so it's like traveling to several different Asian destinations within one country." For truly offbeat adventures, she adds, travelers should head to exotic Malaysian Borneo, which even fewer visitors have explored.

While tourism in Vietnam is still a tiny business when compared to Thailand's massive annual influx, nearly half a million Americans visit the long, narrow nation every year. The typical itinerary includes time to sample the frenetic bustle of Ho Chi Minh City in the south and then the more laid-back colonial elegance of Hanoi in the north. Only a tiny percentage of travelers stop halfway in between in the former imperial capital of Hue, which, though battle-scarred, is still rich enough in history and architecture to have been named a UNESCO World Heritage Site. After exploring the walled Citadel (Vietnam's own Forbidden City), head up the Perfume River to visit the riverside tombs of Vietnam's 19th-century emperors.

Even Sri Lanka, a destination much more popular with Europeans than Americans, has exotic treasures to offer. The seaside city of Galle is starting to attract new international attention. According to Miguel Cunat, who manages upscale travel company SriLankaInStylecom, "To the seasoned traveler it's the new Marrakesh. To the tropical second-home owner it's the new Bali. To the beach lover it's the new Riviera." With its 17th-century Dutch fort, UNESCO World Heritage-quality Dutch colonial architecture and a heavy schedule of festivals and events, Galle — now recovered from 2004 tsunami damage — is having its moment.