Normally, the crust–mantle boundary is thought to be marked by a feature known as the Mohorovičić discontinuity, or ‘Moho’, at which seismic waves change velocity. But at Atlantis Bank, the mantle is thought to bubble up as far as 2.5 kilometres above the Moho, making it easier to reach.

Reaching these deep-Earth frontiers “is one of the great scientific endeavours of the century”, says Henry Dick, a geophysicist at the Woods Hole Oceanographic Institution in Massachusetts and co-leader of the expedition.

Source: Quest to drill into Earth’s mantle restarts : Nature News & Comment