The blue hole is 300.89 meters deep, surpassing the current record of 202 meters, state-run Xinhua news agency reported today.
The hole was found near the Paracel islans called as Xisha Islands by China.
The islands are claimed by China, Vietnam and Taiwan.
China has continued to assert its claim over all but most of the South China Sea even after this month's verdict by the international tribunal appointed by the Permanent Court of Arbitration which has struck down its claims of nine-dash line based on historic rights.
Besides China, Vietnam, the Philippines, Malaysia, Brunei and Taiwan have counter claims over the area.