A Japanese research institute says its deep-sea drilling probe has set a new world record for depth, reaching 7,740 meters (25,400 feet) below the sea surface.

The ‘Chikyu’, operated by the Japan Agency for Marine-Earth Science and Technology, was digging the seabed off Japan’s northern coast to take fault samples and study last year’s devastating earthquake and tsunami.

The agency said on Friday that the probe’s drilling pipe hit the fault zone at 6,883.5 meters (22,600 feet) undersea before reaching the target of 7,740 meters on Wednesday. That’s nearly 8 kilometres (5 miles) deep.

Maritime organizations say the U.S. vessel Glomar Challenger set the previous record of 7,049.5 meters (23,130 feet) below sea surface in the Mariana Trench in 1978.