Mulu Caves & Pinnacles, Sarawak

Gunung Mulu National Park houses four of the world's ten largest cave chambers, led by the Sarawak Chamber at 600 by 415 metres — room for 40 Boeing 747s. Its Pinnacles trail, a two-day hike to 45-metre karst spires, ranks among Southeast Asia's most spectacular goals. The park hosts 3 million bats nightly, and its cave passages extend over 295 kilometres. Named comparisons show it's grander than Sipadan's underwater chambers but requires less technical skill, with a 70% success rate due to steep sections.