BEIJING -- China plans to develop two deep-sea manned submersibles, able to reach a depth of 11 kilometers, by around 2020, according to an oceanic association official.

Liu Feng, secretary-general of China Ocean Mineral Resources R&D Association (COMRA), said that China will upgrade a remotely operated underwater vehicle (ROV) which is able to dive into a depth of 11 kilometers, and put it into operation after testing.

In 2018, China's deep-sea manned submersible Jiaolong, which set a record by diving to a depth of 7,062 meters during tests in the Mariana Trench in June 2012, will officially begin operation.

The Hailong and Qianlong series unmanned submersibles will be improved this year. The former is connected to the support ship by a wire, while the latter is wireless.

China also plans to develop four other high-tech devices for deep-sea exploration to promote sustainable oceanic development, Liu said.

The COMRA, established in 1990, aims to undertake exploration and use of the seabed, ocean floor and subsoil in accordance with international conventions.