Whakaari (White) Island

With its billowing plumes of steam, the active volcano of Whakaari (White) Island makes for an awesome geothermal experience. The island is New Zealand's only active marine volcano—and New Zealand's most active volcano overall. The last major eruption was in 2012, and steam issues continuously from the many fumeroles (vents) and from the central crater, and the area reeks of sulfur. The island itself is eerie but exquisite, with fluorescent sulfuric crystal formations and boiling mud pools.