China's manned deep-sea submersible, Jiaolong, has returned from its 6,965 metre descent to the Mariana Trench.

The submersible, along with its three divers onboard, set a national record after reaching the trench on Monday.

"We sat on the sea bed three times, at a depth of around 6,960 meters each time. We took samples of sediment and surveyed the topography of the sea bed region," said Tang Jialin, one of the divers.

Jiaolong will attempt the feat again in the coming weeks, aiming to reach 7,000 metres.