The newly found volcano lies about 3.4 miles below the sea and covers an impressive 119,000 square miles. For the sake of comparison, the Mauna Loa in Hawaii, which is the largest active volcano on the planet, only covers about 2,000 square miles.

The Tamu Massif’s size brings is closer to what is currently believed to be the largest volcano in the Solar System: the Olympus Mons on Mars. But unlike the Olympus Mons, which has shallow roots, the new Pacific volcano goes about 18 miles deep into the crust of the earth.

It rises about 2 miles above the sea floor, and researchers doubt that its peak ever rose above sea level even when it was still active. Scientists say it is very unlikely that the Tamu Massif ever erupts again.