Vanuatu's Espiritu Santo island peaks at Mount Tabwémasana (1,879 m)—Vanuatu's highest—with volcanic basalt from New Hebrides subduction arc 20 million years ago. Efate's Teouma Ridge reaches 600 m, while Tanna's Yasur (361 m)—active since 1774—emits lava lakes. The chain's central ranges average 800 m, featuring fern forests and 1,000 sinkholes. Formed by Australian-Pacific convergence, Ambrym island's caldera spans 12 km with twin craters. Coastal cliffs drop 100 m to fringing reefs. This volcanic nation includes 4 protected areas with flying foxes and 300 bird species on 83 islands.
