Tanna Island

Tanna is one of the southernmost islands in Vanuatu, lying approximately 200 kilometres south of the capital Port Vila on Efate. It is volcanic — Mount Yasur, at 361 metres, is one of the world's most continuously active volcanoes and one of the most accessible: the crater rim is reached by four-wheel-drive truck from the coast road. The eruption cycle at Yasur is rhythmic — explosions every few minutes, lava bombs arc above the crater, and the glow is visible from the coast after dark. Seismic activity is a constant background to life on Tanna, and the island's soils are exceptionally fertile as a result. The coastal character of Tanna is shaped by its geology. The eastern coast, where Port Resolution sits, is a drowned volcanic caldera — a sheltered bay ringed by black lava cliffs and volcanic black sand beaches. The western coast faces the Coral Sea and receives the full force of the southeast trade wind swell in winter (May to September), with wave energy arriving unattenuated across open ocean from the Southern Ocean fetch. The tidal regime on Tanna is mixed semidiurnal, with spring ranges of approximately 1.0 to 1.2 metres — modest, but sufficient to expose the reef flats and tidal platforms that fringe much of the coastline. Port Resolution is the anchorage most associated with Tanna's exploration history: Captain Cook anchored here in August 1774 during his second Pacific voyage. The bay is a submerged volcanic caldera, and thermal vents on the seabed warm patches of the bay floor, detectable as areas of slightly warmer water. The surrounding beaches are black volcanic sand, and the rugged cliffs that form the bay's rim are covered in dense tropical vegetation. The tidal current inside the bay is gentle even at springs, making it suitable for kayaking. The western coast villages, including White Grass, sit on a clifftop plateau above reef that extends along the Coral Sea shoreline. Access to the reef below requires a descent trail, but the coral cover on this less-visited coast is well-preserved.