QINGDAO - China plans to recruit four to six oceanauts in 2013 as the country vigorously explores the deep sea.

"The national deep-sea base is working on the standards of selection, training and rating of oceanauts," Liu Baohua, director of the base's administrative center, said Thursday.

China currently has three oceanauts -- Ye Cong, Tang Jialing and Fu Wentao, Liu said.

The construction of an expansive deep-sea base, designed to be a state-level oceanic technical support center, is expected to begin later this year or in early 2013, Liu said.

He added researchers with the national base were working on relevant technologies, such as a simulation system of high-pressure oceanic environment and application tools of the manned submersible.

The physical construction of the base will cost 495 million yuan ($77.8 million) and cover 26 hectares of land and 62.7 hectares of sea in the coastal city of Qingdao.

On Wednesday, China's manned submersible Jiaolong set a new national dive record after reaching 7,062 meters below sea level during its fifth dive into the Mariana Trench in the Pacific Ocean.

After arriving at the area earlier this month, Jiaolong had succeeded in reaching depths of 6,671, 6,965, 6,963, 7,020 meters in its first four dives from June 15 to 24, easily surpassing the previous national record of 5,188 meters it set last July.

Besides Jiaolong, named after a mythical sea dragon, the country also plans to build another manned submersible to reach depths of 4,500 meters below sea level, Liu said.

In addition, the base is applying to build a 4,000-tonne mother ship, given that Xiangyanghong 09, the mother ship of Jiaolong, has been in service for over three decades, he said.

The new mother ship is expected to become operational by 2015, he said.