Submarine volcano in the context of "Fonuafo'ou"

Taiwan, officially the Republic of China (ROC), is a country in East Asia. The island of Taiwan, formerly known to Westerners as Formosa, has an area of 35,808 square kilometres (13,826 sq mi) and makes up 99% of the land under ROC control. It lies about 180 kilometres (112 mi) across the Taiwan Strait from the southeastern coast of the Mainland China. The East China Sea is to the north of the island, the Philippine Sea to its east, the Luzon Strait directly to its south, and the South China Sea to its southwest. The ROC also controls a number of smaller islands, including the Penghu archipelago in the Taiwan Strait, Kinmen and Matsu in Fuchien near the Mainland coast, as well as Pratas and Taiping in the South China Sea.

Geologically, the main island comprises a tilted fault block, characterized by the contrast between the eastern two-thirds, consisting mostly of five rugged mountain ranges running parallel to the east coast, and the flat to gently rolling plains of the western third, where the majority of the population resides. Several peaks exceed 3,500 m in height – the highest, Yu Shan at 3,952 m (12,966 ft), makes Taiwan the world's fourth-highest island. The tectonic boundary that formed these ranges remains active, and the island experiences many earthquakes, some of them highly destructive. There are also many active submarine volcanoes in the Taiwan Straits.

The Tonga–Kermadec Ridge is an oceanic ridge in the south-west Pacific Ocean underlying the Tonga–Kermadec island arc.It is a result of the most linear, fastest converging, and seismically active subduction boundary on Earth, the Kermadec–Tonga subduction zone, and consequently has the highest density of submarine volcanoes.

The Tonga–Kermadec Ridge stretches more than 3,000 km (1,900 mi) north-northeast from New Zealand's North Island. The Pacific Plate subducts westward beneath the Australian Plate along the ridge. It is divided into two segments, the northern Tonga Ridge and southern Kermadec Ridge, by the Louisville Seamount Chain. On its western side, the ridge is flanked by two back-arc basins, the Lau Basin and Havre Trough, that began opening at 6 Ma and 2 Ma respectively. Beyound the basins is the Lau-Colville Ridge. Together with these seafloor structures the ridge forms the eastward-migrating, 100  million year old Lau–Tonga–Havre–Kermadec arc/back-arc system or complex.

Hunga Tonga–Hunga Haʻapai (listen) is a submarine volcano in the South Pacific located about 30 km (19 mi) south of the submarine volcano of Fonuafoʻou and 65 km (40 mi) north of Tongatapu, Tonga's main island. It is part of the highly active Kermadec-Tonga subduction zone and its associated volcanic arc, which extends from New Zealand north-northeast to Fiji, and is formed by the subduction of the Pacific Plate under the Indo-Australian Plate. It lies about 100 km (62 mi) above an active seismic zone. The volcano rises around 2,000 m from the seafloor and has a caldera which on the eve of the 2022 eruption was roughly 150 m below sea level and 4 km at its widest extent. The only major above-water part of the volcano are the twin uninhabited islands of Hunga Tonga and Hunga Haʻapai, which are respectively part of the northern and western rim of the caldera. As a result of the volcano's eruptive history, the islands existed as a single landmass from 2015 to 2022: they were merged by a volcanic cone in a volcanic eruption in 2014–2015, and were separated again by a more explosive eruption in 2022, which also reduced the islands in size. The Hunga Tonga–Hunga Haʻapai volcano has seven historical recorded eruptions.

The most recent eruption, in January 2022, triggered a tsunami that reached the coasts of Japan and the Americas, along with a volcanic plume that soared 58 km (36 miles) into the mesosphere. It was the largest volcanic eruption since the 1991 eruption of Mount Pinatubo and the biggest explosion recorded in the atmosphere by modern instrumentation, far surpassing any 20th-century volcanic event or nuclear bomb test. NASA determined that the eruption was "hundreds of times more powerful" than the atomic bomb dropped on Hiroshima. It is believed that the 1883 eruption of Krakatoa is the only eruption in recent centuries that rivaled the atmospheric disturbance it produced. The January 2022 eruption is the largest volcanic eruption in the 21st century.

Whakaari / White Island ([faˈkaːɾi], Māori: Te Puia Whakaari, lit. "the dramatic volcano"), also known as White Island or Whakaari, is an active andesite stratovolcano situated 48 km (30 mi) from the east coast of the North Island of New Zealand, in the Bay of Plenty. The island covers an area of approximately 325 ha (800 acres), which is just the peak of a much larger submarine volcano.

The island is New Zealand's most active cone volcano, and has been built up by continuous volcanic activity over the past 150,000 years. The nearest mainland towns are Whakatāne and Tauranga. The island has been in a nearly continuous stage of releasing volcanic gas at least since it was sighted by James Cook in 1769. Whakaari erupted continually from December 1975 until September 2000, and also erupted in 2012, 2016, and 2019.

Kamaʻehuakanaloa Seamount (previously known as Lōʻihi) is an active submarine volcano about 22 mi (35 km) off the southeast coast of the island of Hawaii. The top of the seamount is about 3,200 ft (975 m) below sea level. This seamount is on the flank of Mauna Loa, the largest active subaerial shield volcano on Earth. Kamaʻehuakanaloa is the newest volcano in the Hawaiian–Emperor seamount chain, a string of volcanoes that stretches about 3,900 mi (6,200 km) northwest of Kamaʻehuakanaloa. Unlike most active volcanoes in the Pacific Ocean that make up the active plate margins on the Pacific Ring of Fire, Kamaʻehuakanaloa and the other volcanoes of the Hawaiian–Emperor seamount chain are hotspot volcanoes and formed well away from the nearest plate boundary. Volcanoes in the Hawaiian Islands arise from the Hawaii hotspot, and as the youngest volcano in the chain, Kamaʻehuakanaloa is the only Hawaiian volcano in the deep submarine preshield stage of development.

Kamaʻehuakanaloa began forming around 400,000 years ago and is expected to begin emerging above sea level about 10,000–100,000 years from now. At its summit, Kamaʻehuakanaloa Seamount stands more than 10,000 ft (3,000 m) above the seafloor, making it taller than Mount St. Helens was before its catastrophic 1980 eruption. A diverse microbial community resides around Kamaʻehuakanaloa many hydrothermal vents.