Teams utilize state-of-the-art technology to examine and study underwater archaeological findings to bring them to the public, Chen Bowen reports in Qionghai, Hainan.

In the waters 150 kilometers southeast of Sanya, South China's Hainan province, lie two ancient shipwrecks enveloped in a shroud of mystery, resting beneath 1,500 meters of deep blue sea.

The shipwrecks, discovered in October 2022 and traced back to the middle of the Ming Dynasty (1368-1644), have been named by researchers as "Northwest Continental Slope No 1 and No 2 Shipwrecks in the South China Sea".

The two shipwreck sites are relatively well-preserved and contain a wealth of cultural artifacts with a clear historical context, said Song Jianzhong, a researcher at the National Centre for Archaeology of the National Cultural Heritage Administration.

"This discovery not only stands as a major achievement in deep-sea archaeology within China, but it also holds global significance as a world-class archaeological find," he added.

Archaeological investigations have confirmed that the core area of No 1 Shipwreck, housing the primary accumulation of the hull and a significant amount of neatly stacked cargo, spans 37 meters in length and 11 meters in width.

It is estimated that over 100,000 cultural relics, including porcelain, pottery, bronze, ironware, bamboo and wood are hidden on the spot, with much of No 1 Shipwreck still submerged under sand. Some of its exposed sections are buried by up to three meters of artifacts.

Some porcelain pieces have inscriptions and markings on them, such as "Fu" (happiness and blessing), "Taiping" (peace), and "Made by Wu Wen", providing clues about the origin, production and possible ownership of these items.

Located about 20 kilometers away from No 1 Shipwreck, No 2 Shipwreck has been delineated into a core area and a scattered area. The core area, stretching 21 meters in length from north to south and 8 meters in width from east to west, showcases orderly stacked logs. In contrast, the scattered area presents an assortment of artifacts including pottery, shells and dispersed logs.

The stable physicochemical properties of seawater and the excellent acid and alkali resistance of ceramics enable these artifacts to be preserved underwater for centuries, said Li Jian'an, a researcher from the Fujian Museum.

"These artifacts are pioneering archaeological findings, serving as witnesses to the trade interactions along the ancient Maritime Silk Road in China. They offer tangible evidence that sheds light on China's maritime history and the cultural exchanges between Chinese civilization and foreign cultures," Song said.

Crucial findings unveiled

In a series of archaeological investigations that commenced in May 2023 on the two ancient shipwrecks, researchers have retrieved a collection of 928 pieces of cultural relics, with some undergoing a desalination treatment in deionized water. The extensive efforts involve three stages of exploration and 63 dives, the National Cultural Heritage Administration announced during a press conference in China (Hainan) Museum of the South China Sea in Qionghai, Hainan on June 13.

In the exploration of No 1 Shipwreck, the focus has predominantly been on porcelain artifacts, including blue-and-white, celadon and fahua wares. Fahua refers to Chinese porcelain with bold, deep blue decorations and glazes in turquoise, purple, green, yellow and white. While major museums worldwide house fahua wares mostly passed down through generations, archaeological findings of such wares have been rare, making their discovery in the shipwreck a first. To date, several fahua wares, including jars and prunus vases, have been retrieved from the sunken vessel.

The discovery of fahua wares in No 1 Shipwreck validates their exportation from Jingdezhen, Jiangxi province — recognized as China's "porcelain capital" — as commodities during the mid-Ming Dynasty, according to Li. He further noted that this discovery not only illuminates the quest for associated production kiln sites but also provides concrete evidence to elucidate the origins of fahua wares in foreign regions.

The third phase of exploration, conducted in May and June, achieved a significant breakthrough by establishing a chronology through the finding of a red-and-green-colored bowl dated to 1506.The year, marking the commencement of Emperor Zhengde's reign in the mid-Ming Dynasty, solidifies earlier assessments that No 1 Shipwreck originates from the Zhengde era (1506-21).

"This precise dating connects the shipwreck to a specific year, improving our comprehension of its historical significance," said Song.

He noted that No 1 Shipwreck carried a load of porcelain, presumably earmarked for export to Southeast Asia. In contrast, the second shipwreck was found to have been transporting mainly timber homeward from overseas.

"This marks the world's initial discovery of ancient merchant vessels in the same area, believed to be privately owned merchant ships," Song said.

State-of-the-art tech

In 2023, the National Centre for Archaeology, the Institute of Deep-sea Science and Engineering of the Chinese Academy of Sciences and the China (Hainan) Museum of the South China Sea joined forces to form a team, which pooled expertise from various fields to undertake research, excavation and preservation activities linked to underwater cultural heritage. Employing cutting-edge deep-sea technology, the team utilized the scientific research vessels Tansuo 1 and Tansuo 2, alongside the manned submersible Shenhai Yongshi (Deep-Sea Warrior), for an archaeological expedition at the two shipwreck sites.

The long baseline positioning system, for example, has revolutionized the accuracy of positioning, navigation and labeling of positions, making mapping underwater terrain more precise. With the system, "we have increased the update rate of underwater positioning from the previous 60 seconds to 3 seconds, providing divers with real-time navigation reference without delays", said Chen Chuanxu, deputy head of the scientific department of the Institute of Deep-sea Science and Engineering.

The Shenhai Yongshi is equipped with three-dimensional laser scanning and high-definition cameras to capture panoramic images and create detailed 3D scans of the shipwreck sites' distribution area.

Precise positioning and 3D reconstruction of all artifacts at the sunken shipwreck sites are required for underwater archaeological operations, according to Chen.

"In the depths of 1,500 meters, these present new challenges to our previous techniques for underwater positioning and measurement," he said. "To meet the demand, upgrades were made to the manned submersible platform and detection payloads to integrate information such as position, altitude, speed and synchronized clock into a laser-scanning device for high-precision 3D mapping."

The Shenhai Yongshi is also outfitted with an enhanced manipulator system. "The traditional rigid material manipulator claws have been replaced with claws made of flexible materials, ensuring the stable extraction of underwater artifacts while preserving the precious details and patterns on the surface of the artifacts for further study and conservation," said diver Deng Yuqing from the Institute of Deep-sea Science and Engineering.

Extensive sampling of submarine sediment, seawater and marine organisms has also been carried out, providing data for environmental analysis and understanding of the ecosystem surrounding the shipwreck sites.

Since its presumable submersion in 1506, the gradual alterations within No 1 Shipwreck have intertwined with marine life and the micro-environment on the seabed. This symbiotic relationship has fostered the development of a distinctive underwater ecosystem, giving rise to a fragile ecological chain encircling the sunken vessel. "The retrieval and examination of samples, encompassing mud samples from the seabed, sediment from the ocean floor, and the microorganisms therein, represent pivotal measures in comprehending and conserving the shipwrecks for posterity," Song said. "Through the analysis of these samples, our objective is to amass scientific data that will assist us in effectively safeguarding these historical sites and the ecosystems enveloping them."

Over the past year, over 200 individuals took part in the collaborative team efforts for detailed data recording, precise photo stitching and the methodical execution of archaeological procedures. Across the three stages, the team established standardized protocols, enhanced processes and introduced innovative methodologies. "These developments have established a strong foundation for our future deep-sea archaeological expeditions, especially in the South China Sea," said Song.

The three stages of exploration "fully showcase the integration of China's deep-sea technology and underwater archaeology, marking a significant step forward towards international advanced levels," said Guan Qiang, deputy director of the National Cultural Heritage Administration.

Relics to be exhibited

The collaborative team is immersed in tasks such as cleaning, protecting, restoring, measuring, registering and organizing the retrieved artifacts. Upon meeting exhibition criteria, selected artifacts will be unveiled in the exhibition hall of the China (Hainan) Museum of the South China Sea before this year's National Day holiday, providing the public with an opportunity to admire these cultural relics, according to Xin Lixue, director of the museum.

He said that advanced technologies will be harnessed for the restoration and virtual display of the sunken ships' hulls, offering a vivid portrayal of the conditions at the sites. This approach will be guided by the ongoing progress in archaeological endeavors and research conducted at the shipwreck sites.