Two hidden mountains, more than 100 times larger than Mount Everest have been discovered deep underground. The two ‘islands of rock’ each measure more than 620 miles / 998km tall, dwarfing anything found on Earth’s surface and making Mount Everest look like an anthill.

Deep within Earth’s mantle lie two enormous regions, often referred to as "islands," which are the size of continents.

Earth's biggest mountains, more than 100 times taller than Mount Everest, have been discovered on the boundary between Africa and the Pacific Ocean, a groundbreaking research, published in the journal Nature,