Significant achievements have been made in the joint voyage of the "Tansuo-1 (Explorer-1)" and "Tansuo-2 (Explorer-2)" research vessels in the northern part of the South China Sea, with 66 cultural relics discovered, according to the Institute of Deep-sea Science and Engineering (IDSSE) under the Chinese Academy of Sciences (CAS).

According to researchers, at one underwater cultural relic site, three ship hulls and multiple glazed jars were found on the seabed at a depth of between 2,000 and 3,000 meters. This is the first time the country's underwater archaeological excavation has exceeded the depth of 1,000 meters, a record set in 2018.

"The discovery of deep-sea archaeology is mainly due to the introduction of unmanned deep diving technology and the combination of manned and unmanned deep diving technology," said Chen Chuanxu, an associate researcher at the IDSSE.

"We first applied acoustic deep-tow to conduct a large-scale search, which can search for about 100 square kilometers per day and find objects of one-meter size. After identifying the suspected location, we will arrange AUV (autonomous underwater vehicle) to take underwater photos continuously. If we can find shipwrecks or suspected cultural relics in the photos, we will arrange manned deep diving for underwater verification and confirmation and the extraction of cultural relics," he explained.

Such high-tech collaboration has enhanced the exploration capabilities of maritime scientific research and greatly improved the efficiency. Researchers have carried out image data extraction, three-dimensional laser scanning, environmental and ship sediment and wood samples collection, and extracted 66 cultural relics such as pottery, porcelain, purple clay ware, copper coins and ship plates.

"The survey enables us to have an understanding of the distribution and the preservation status of underwater cultural relics, especially the shipwreck relics in deep sea," said Deng Qijiang, deputy director of the Institute of Underwater Archaeology under the National Center for Archaeology.

Through this exploration, the team has explored a complete workflow of deep-sea archaeological investigation and accumulated experience for the future search and discovery of cultural relics in deep sea, Deng said.

The follow-up team will conduct in-depth studies on the age and source of the ship hulls.