Relaxing — deep, immediate muscle release.
Rich in active gases or metals — a strong mineral character.
Soft water — natural, classic buoyancy.
Niuafo'ou island — Tin Can Island — in the far north of the Tongan archipelago is one of the Pacific's most remote and volcanically active islands, an almost perfectly circular caldera rising from the deep ocean, whose extremely hot beach springs are heated by geothermal activity from the still-active Niuafo'ou volcano. The bicarbonate hot springs emerge on the island's black volcanic beaches at scalding temperatures, moderated by mixing with ocean water in the intertidal zones to create natural warm bathing conditions unique in the Pacific. Niuafo'ou's extraordinary isolation — it was historically accessible only by mail dropped in a sealed tin can floated to shore, giving rise to its nickname — has preserved it as one of the most culturally and geologically authentic Polynesian islands. The island's endemic Niuafo'ou megapode, a bird that uses volcanic heat to incubate its eggs, and its traditional Tongan culture intact after centuries of isolation, add remarkable dimensions to any visit.