Two small islands that sit atop the waves in the northern part of the Pacific Ocean are actually the peaks of the largest volcano in the world, according to a new study.

Pūhāhonu, which means "turtle rising for breath" in Hawaiian, is located about 1,100 kilometers northwest of Honolulu. It is a shield volcano that rises to around 4,500 meters from the ocean floor and has only one lava source.

In an analysis published last month, researchers estimate that Pūhāhonu has around 150,000 cubic kilometers of mass. However, only a third of that mass is above the sea floor, while the rest is buried under materials eroded from the summit. The volcano is so large that it has caused the surface of the nearby Earth to sink hundreds of meters over millions of years.