The Apolaki Caldera is a volcanic crater with a diameter of 150 kilometers (93 mi), making it the world’s largest caldera. It is located within the Benham Rise (Philippine Rise) and was discovered in 2019 by Jenny Anne Barretto, a Filipina marine geophysicist and her team. The name “Apolaki” means “giant lord” in Filipino, and is also the name of the god of sun and war in some pantheons in Philippine mythology and the indigenous Philippine folk religions.

A team of marine geophysicists published a paper describing a large igneous massif east of the island of Luzon, located on the bottom of the Philippine Sea. Gravimetric analysis shows that the Benham Rise, as the submarine mountain massif is named, is made up of a nine mile thick layer of magmatic and volcanic rocks. Rock samples ages range from 47.9 to 26 million years, when volcanic activity made up the massif.

The Benham Rise is rising from the 5.200 meters deep seafloor to ~2500 meters beneath the sea surface, with a depression in the central portion, which likely is a volcanic caldera. When large volumes of magma are erupted over a short time, a volcano may collapses downward into the emptied or partially emptied magma chamber, leaving a massive depression at the surface, from one to dozens of kilometers in diameter.

The circular depression on the Benham Rise is surrounded by a crest with scarps as high as 100 to 300 meters. It is the world’s largest known caldera with a diameter of ~150 km. For comparison, the famous caldera of Yellowstone in Wyoming is only about 60 km wide. The researchers named the caldera Apolaki, meaning “giant lord”, after the Filipino god of the sun and war.

According to forbes.com