West Mata is an active submarine volcano located in the northeastern Lau Basin, roughly 200 km (124 mi) southwest of the Samoan Islands. It is part of the Tonga-Kermadec volcanic arc, which stretches from the North Island of New Zealand to Samoa. The volcano was first discovered in 2008 by scientists aboard the R/V Thompson research vessel, using sonar mapping and a remotely operated vehicle (ROV) to explore the seafloor. At the same time West Mata was discovered, multiple neighboring volcanoes—most of them hydrothermally active—were discovered as well, including Volcano O, Tafu-Maka, Northern Matas and East Mata.