BEIJING, Jan. 23 (Xinhua) -- China plans to develop two deep-sea manned submersibles capable of reaching 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) able to dive to a depth of 11 kilometers, and will 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 of unmanned submersibles will be improved this year. The former is connected to a 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.

He said that the association will help establish a branch of the Qingdao-based National Deep Sea Center in south China's Hainan Province, a sea sample collection center and a comprehensive system for deep-sea monitoring.

The COMRA will focus on the development of underwater gliders that can dive to depths of 1 km and 4.5 km to monitor the deep-sea environment over vast areas.

The association will also increase the efficiency of offshore operations in line with the needs of surveying the deep-sea environment, resources, safety and pollution.

In 2018, six voyages lasting a combined 650 days at sea will be carried out for comprehensive marine surveying, Liu said.

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