With more than 17,000 islands – ranging from palm-fringed islets to the leviathan bulk of Sumatra – Indonesia's natural diversity is showcased amid more than 1.9 million sq km straddling the equator and stretching from the Indian Ocean to the Pacific. Volcanic peaks rise from lush jungle, the underwater world is revealed in the planet's finest diving locations, and surprising wildlife ranges from giant reptiles to gentle denizens of the forest.
Komodo National Park
Sunbaked and barren, Komodo stands apart from other more verdant Indonesian islands, and the island's most celebrated species is also singular and surprising. The world's biggest lizard can grow up to three metres-long, and Komodo dragons are often seen lumbering along the beach by visitors arriving at the national park's main camp at Loh Liang. Guided walks with national park staff continue for 30 minutes to a dry riverbed at nearby Banu Nggulung where the huge monitor lizards are often seen. Two-day/one-night boat trips to Komodo depart from raffish Labuanbajo on nearby Flores, and day trips to Rinca – where the dragons also roam – are possible from Labuanbajo.
Tanjung Puting National Park
Wildlife watching and river adventures combine in this massive 4150 sq km park in central Kalimantan, the Indonesian southern part of Borneo. Rustic but comfortable river boats travel up the Sungai Sekoneyer, stopping at orangutan feeding stations during a three-day journey en route to Camp Leakey, a rehabilitation centre where orphaned and formerly captive orangutans are trained to live in the wild. Stellar birdlife including darting kingfishers and regal hornbills is often revealed along the river's banks, and local operators including Borneo Orangutan Adventure Tour can arrange private trips on the Sekonyer's signature two-storey teak houseboats dubbed klotok.
Raja Ampat Islands
Remote near the northwestern tip of far-flung Papua Island, the scattered waters of Raja Ampat host the world's greatest diversity of marine life. Above a translucent ocean, rounded hills enrobed in tropical forest surround a labyrinth of compact coves and improbably small islets, providing sublime diversion to the underwater spectacle. Manta rays and epaulette sharks drift through a technicolour seascape of pristine coral, while shoals of barracuda and parrotfish patrol the diverse marine terrain punctuated with underwater walls, peaks and ridges. Snorkelling, kayaking and birdwatching are all essential attractions for non-divers, and live-aboard boat cruises – often on Bugis-style heritage schooners – are the best way to explore Raja Ampat.
In a country studded with volcanoes, the surreal beauty and immense scale of Java's Mt Bromo is one of Indonesia's most epic natural spectacles. A vast crater – 10km across and created by the violent volcanic history of the ancient Tengger caldera – is punctuated by the oft-smouldering peak of Bromo. Immense plains of ash and volcanic sand extend to the crater's towering cliffs, and the nearby peaks of Kursi and Batok stand as sinister companions to Bromo's bulk. Sunrise is when the horizon-filling crater is seen at its best, and 4WD excursions leave from the nearby town of Cemoro Lawang at around 3:30am to capture a terracotta landscape infused with the bronzed half-light of a Javanese dawn.
Soaring to 3726m, Mt Rinjani is Indonesia's second tallest volcano, and the mountain's majestic profile dominates northern Lombok. Sacred both to Lombok's Sasak people and to the Hindu residents of nearby Bali, Rinjani's finest feature is a 6km-wide lake of shimmering cobalt blue encompassing the summit's huge caldera. Conquering Rinjani is most usually achieved on a three-day/two-night excursion. Rudy Trekker in the nearby village of Senaru has experienced guides.
Located amid northern Sumatra's volcanic peaks at a height of 1130m, Danau Toba encompasses the caldera of a super-volcano known to be the world's largest volcanic lake. Intense ocean-blue waters cover an expanse 100km in length, framing the wedge-shaped island of Pulau Samosir, home to the region's Batak people. Sleepy roads perfect for biking fan throughout the island and along the lake's edge, making Toba a favourite for travellers taking time out from exploring other parts of Indonesia.
Kelimutu National Park
Best discovered at sunrise after a meandering minibus journey from nearby Moni, three intensely coloured volcanic lakes sit atop the summit of Kelimutu on the eastern island of Flores. Two of the exceptionally deep crater lakes regularly change colour – driven by the continuous leaching of different minerals – and the indigo smudge of a Flores dawn illuminates contrasting hues ranging from brown and orange through to black and red. All the while, Kelimutu's third lake is daubed an iridescent shade of turquoise, glowing through the half-light slowly revealing Kelimutu's sparse lunar landscape.
Easily reached from the Sumatran mountain town of Bukittinggi, the Harau Valley is fringed by soaring limestone cliffs up to 100 metres high and enlivened by the Lemba Harau waterfalls. Rock-climbers negotiate careful routes up the cliffs, while walking trails meander through emerald-green rice paddies to the valley's quicksilver cascades. Comfortable homestay accommodation in the architectural style of West Sumatra's Minangkabau people sits amid cooling lotus ponds. Transport and accommodation for the Harau Valley can be arranged with Lite 'N' Easy Tour in Bukittinggi.
Pulau Gunung Api Banda
With a perfectly conical profile – resembling Japan's Mt Fujiyama, but only 666m high – the compact island peak of Gunung Api in the remote Banda Islands is one of Indonesia's most picturesque volcanoes. The challenging slope of volcanic scree can be conquered in around three hours, perfect timing to witness another spectacular Indonesian sunrise. Later in the day, submerged lava flows off Gunung Api's northern coast provide another opportunity for good snorkelling.
Located just off Bali's northwestern tip, Pulau Menjangan ('Deer Island') is one of Indonesia's most accessible locations for both experienced divers and adventurous snorkelling fans. The surrounding Bali Barat National Park ensures protection for twelve different dive sites, and the crystalline waters showcase sheer walls, caves and a spectacular drop off. Expansive corals and shapeshifting schools of tropical fish create an underwater ambience akin to swimming in a giant aquarium – a marine spectacle achievable even by relatively novice snorkellers. For experienced divers the fascinating 19th-century wreck of the Anker lies at a challenging depth of around 50m.