JINAN, June 15 (Xinhua) -- Ten meters below the ocean surface off Wuzhizhou Island of the south China island province of Hainan, a small robotic inspector glided silently among branching corals. Seen via its cameras were hawksbill turtles, parrotfish and a reefscape that, a decade ago, was nearly dead.
The island's marine ranch once faced coral collapse. Since 2010, artificial reefs have helped restore this habitat, but monitoring it had remained a problem.
"We used to rely on manual diving. It's inefficient and risky," said Wang Aimin, a professor at Hainan University and chief scientist of the Hainan Provincial Engineering Research Center for Modern Marine Ranching.
The turning point came through collaboration with Robotfish, a marine technology firm based in Qingdao, a coastal city in China's eastern Shandong Province.
Its underwater robot can operate for hours with minimal disturbance, capturing close-up, multi-angle images of coral health. Today, seven information monitoring stations form a round-the-clock surveillance network in this area of Hainan, tracking water temperature, salinity and live reef activity.
"If something goes wrong, we can act immediately," Wang said.
China's homegrown marine "black tech," from intelligent robots to ocean AI models, is rapidly entering real-world applications such as ecological protection, disaster forecasting and shipping services, as the country steps up efforts to strengthen marine strategic science and technology and promote intelligent and digital transformation in the marine sector.
Monitoring a coral reef is benign compared to what the ocean can throw at a machine. GPS signals do not penetrate seawater. Pressure rises one atmosphere every 10 meters. Biofouling, corrosion and unpredictable currents degrade equipment within weeks.
One cannot simply adapt land-based tech, but must rebuild it from first principles, said Wang Fan, director of the Institute of Oceanology under the Chinese Academy of Sciences (IOCAS).
Wang Fan added that the ocean remains one of the least instrumented places on the planet, while marine data is sparse and expensive to collect.
This is precisely the logic behind a new wave of marine AI models being developed in coastal hubs like Qingdao, also known as the "capital of marine science" in China, for hosting nearly one-third of the country's high-level marine research institutions.
At a recent Digital Earth conference held there, the IOCAS on June 6 unveiled LangYa 2.0, an ocean AI model that forecasts typhoons, precipitation, sea ice, storm surges, internal solitary waves and mesoscale eddies.
This new model's six vertical models put predictions into forms that policymakers and coastal residents can actually use.
The engineering model behind LangYa 2.0 correctly predicted several sudden-turning typhoons last year, improving 24-hour forecast accuracy by more than 10 percent, said Wang Fan.
"With lightweight versions of large models, we can deploy them locally. That offers a low-cost forecasting option for less developed countries and regions," he said.
The IOCAS also plans to carry out collaborative research with more countries and regions within the framework of the United Nations Decade of Ocean Science for Sustainable Development (2021-2030), he noted.
If AI helps humans understand the sea, intelligent robots provide sharp "eyes" and dexterous "hands and feet" to see and move beneath the waves.
In the Strait of Malacca, one of the world's busiest shipping lanes, multiple fourth-generation underwater cleaning robots from ZhiZhen Marine Science and Technology (Weihai) Co., Ltd. in Shandong Province are scraping barnacles and algae off vessel hulls.
"Biofouling increases drag and fuel consumption, and can shorten a ship's lifespan. Traditional manual cleaning is inefficient, risky and no longer fits modern shipping," said Qin Mingda, head of the company's cleaning robot project.
ZhiZhen's robots operate at depths of up to 150 meters, cleaning 2,000 square meters per hour, work which would have required four skilled divers. In 2025, these robots cleaned over a thousand ships in Malacca waters, becoming the only type of equipment capable of stable operation there, according to Qin.
"Singapore clients keep ordering as many units as we can make," he revealed.
Such niche breakthroughs, however, do not scale by themselves. They demand policy coordination and this is exactly what China's central government has set out to provide.
China has made marine technology a national strategic priority as its marine economy had exceeded 11 trillion yuan (about 1.6 trillion U.S. dollars) in 2025, up 5.5 percent year on year. In March, a senior National Development and Reform Commission official, Yuan Da, told a State Council briefing that China's 15th Five-Year plan (2026-2030) dedicates a separate chapter to improving maritime capabilities and accelerating the construction of maritime power.
Yuan laid out priorities including strengthening marine strategic science and technology to promote innovation-driven growth, and promoting digital and intelligent transformation in the marine sector.
The Ministry of Natural Resources has echoed this urgency, calling in March for "using green and digital-intelligent technologies to transform and upgrade traditional marine industries."
For Qin, ZhiZhen is not resting on its market success. A fifth-generation cleaning robot is now being tested, with optimized designs for better cleaning efficiency and sea-state adaptability. "Innovation is the key to go deeper in the sea," he said. ■
