The climate is tropical - hot and humid all year round, with only two seasons: wet, which usually occurs in winter, and dry in summer, although there are significant local variations and expedition planners take the weather into account when creating their itineraries. You will access this region through a South East Asian gateway, usually Singapore or Hong Kong. Onward flights may be scheduled, or specially chartered specifically for your journey.
Some routes include Java and the extraordinary temple complex at Borobudur, and call in at Lombok, dominated by the huge crater of Gunung Rinjani, while the south and west coasts are home to some stunning beaches. Volcanoes another draw of this region, including the city of Probolinggo on the north coast of East Java, the jumping off point for excursions to Bromo-Tengger-Semeru National Park where the smouldering Mount Bromo and Mount Semeru loom over the fertile volcanic plains and the island of Krakatoa where the world's most famous volcanic eruption in history took place, home to the still-active Anak Krakatau, the 'child of Krakatoa'.
Of course, they are both gateways to Bali, at the south of the Indonesian archipelago - arguably the region's most famous. Though the island is not the undiscovered gem it once was, it's still a wonderful place to travel. The beaches, spectacular volcanic scenery and lush green rice terraces lend Bali a natural beauty that seems to dovetail perfectly with the island's distinct Hindu culture, which adorns the landscape with stunning temples. Steer clear of the backpacker beaches around Kuta and head instead for the quieter south coast resorts or the charming inland town of Ubud, the spiritual centre of the island.
Sumbawa is just to the east of Bali and Lombok, though the island is drier, less developed and more conservative than its neighbours. It's a popular spot for surfers, and home to sleepy villages where locals weave indigo cloth and build traditional wooden boats by hand.
Sulawesi, north of Bali, with Borneo to the east, is home of the Torajan people with their captivating villages, dramatic death rituals and timeless traditions. Then, Borneo, part of the Greater Sunda Islands, shared between Indonesia, Malaysia and Brunei - with the Indonesian section (called Kalimantan) making up 75% of the island - is home to rainforests that are among the richest and most biodiverse on Earth. You might see the pygmy elephant, the shy Borneo rhino, the remarkable orangutan, the proboscis monkey with its large nose and belly, six other primate species, as well as 220 bird species including parrots, lorikeets, the spectacular bird of paradise and hornbills, carnivorous pitcher plants and gigantic fruit bats, also known as flying foxes.
Neighbouring Komodo Island is situated within an area of spectacular natural beauty and is arguably most well most known for its eponym, the famous Komodo dragon. The stunning beaches are tinged with pink thanks to the high concentration of red coral just offshore, and the waters draw intrepid divers from all over the world.
Back in Bali, head east to discover the island of Flores, home to some of the most staggeringly beautiful scenery in the Indonesian archipelago, a lush landscape of smouldering volcanoes, spectacular lakes and verdant paddy fields, with its waters home to manta rays, whales, and several species of turtle. Flores is also culturally distinct from the other islands, with a population that is 95% Catholic.
Sail northwards - sometimes via East Timor, where marine life fills coral reefs in what is one of the world's youngest nations, only made independent in 2002 from Indonesia - to the Banda Archipelago, also known as the Moluccas or Spice Islands, thanks to the Myristica trees that produce nutmeg and mace.
Of this group of ten small volcanic islands, the only significant settlement is on Banda Neira, with its hotchpotch of European colonial buildings, while off the coast you can enjoy some fantastic diving and snorkelling.
Other highlights in this area include the indigenous tribal groups of Alor Island, with the outer archipelago a fantastic destination for snorkelling and diving, as well as the Kai archipelago, known for its idyllic beaches. The ancestors of the Kai people are believed to have come here from Bali, but there is no written history, with an oral tradition of stories known as Tom-Tad that are passed down from generation to generation.
The protected marine reserve of Triton Bay also rivals Raja Ampat as one of Indonesia's premier locations for snorkelling and scuba diving. The biodiversity here is remarkable, with species ranging from pygmy seahorses to mighty whale sharks, and it's also a nesting site for green turtles.
North of the Spice Islands, east of Papua, you'll find one of the crowning jewels of the region - the glorious Raja Ampat. Routes often begin in Darwin at the top of Australia to get to the exotic isles and marine biodiversity haven located in the heart of the Coral Triangle, a high-definition world of sugarloaf limestone towers, draped in bottle green jungle and scattered across 15,000 square miles of aquamarine sea.
Two thirds of the world's coral species are found here, and more than 1,600 species of reef fish, in carnival colours of electric blue, shocking pink and sunshine yellow. You don't need to be a diver to appreciate the extraordinary underwater world, from dazzling coral gardens and underwater canyons where black-tipped reef sharks cruise the blue depths.
New Guinea Island is Indonesia's easternmost province, half of which is made up of West Papua, situated at the heart of the 'Coral Triangle', an incredible biodiversity hotspot. The warm waters are home to colourful tropical fish, green and hawksbill turtles, manta rays and walking sharks, and it's a popular destination for scuba divers.
But the star attraction is Cenderawasih Bay, known as the 'whale shark capital of the world'. Encounters with whale sharks in the wild are normally fleeting, but in Cenderawasih Bay these giant creatures linger close to the surface to feed on small fish that spill from the nets of the local fishermen, and it's normal to see four or five whale sharks on a single dive.
Next door, the extraordinary land of Papua New Guinea greets you with famous Asmat wood carvings, explore ancient rock art, and people completely isolated from the western world. Dedicated anthropologists and archaeologists over the past century have learnt much about the friendly and hospitable people in this region, and this is an opportunity to understand their histories, their belief systems and their way of life.
You'll also find mountains for hiking or sightseeing, spotting marsupials such as monkeys, sloths, possum, koala and tree-kangaroos, while the waters offer extraordinary marine biodiversity including beautiful corals, such as staghorn, elkhorn, brain, pillar, star, and mushroom corals as well as species such as rays, sharks, sperm whales, a variety of seabirds and several turtle species, with plenty more colourful tropical reef fish too numerous to name.
