China’s Dream Ship Drills 5,000m Deep-Sea Basalt
China’s first domestically designed ocean drilling vessel, the Mengxiang (“Dream”), has completed a landmark South China Sea trial and recovered basalt samples from the deep-sea ocean basin, lifting the country’s deep-sea core-sampling capability to the 5,000-meter level, according to People’s Daily.
The achievement makes China the third country — after the United States and Japan — to use a drilling ship to recover hard-rock samples from a deep-sea ocean basin. The voyage, which returned to Guangzhou in Guangdong province, was organized by the China Geological Survey and implemented by the Guangzhou Marine Geological Survey.
A 30-Day Voyage in 4,100-Meter Water
The 30-day mission drilled and cored two boreholes in the South China Sea at a water depth of roughly 4,100 meters, the China Geological Survey announced on September 28.
The ship’s maximum completion (total) drilling depth reached 4,929.17 meters, while its maximum footage for the operation hit 864.77 meters — a new record for China’s self-operated maximum operating water-depth drilling. Using a self-developed rotary coring tool, the team recovered a 4.27-meter basalt core sample. A separate photo caption recorded a single-run core of 8.54 meters.
According to Xinhua, the team built a coring operation system comparable to the International Ocean Discovery Program (IODP) standard, with several coring runs exceeding a 100% recovery rate — reaching advanced international levels in efficiency, quality and operational stability.
Why Drilling Hard Rock Matters
Recovering intact core from deep-sea basalt is exceptionally difficult. According to Sun Zhen, a researcher at the Guangzhou Marine Geological Survey and chief scientist of the voyage, deep-sea basalt typically lies in 1,000 to 7,000 meters of water and is both extremely hard and brittle.
“Normally it is very difficult to obtain a relatively complete core, so drilling hard rock requires both capability and technique,” Sun told CNR / Voice of China. “So recovering hard rock from the deep seafloor of the South China Sea is something we are proud of — it is quite difficult.”
She noted that in the South China Sea, even seamounts standing high above the seabed are frequently covered by hundreds of meters of sediment, meaning a drill must first penetrate that layer before reaching hard rock.
The mission also marked a milestone in underwater robotics and at-sea analysis. The team conducted the first long-duration, high-intensity coordinated operation of shipborne deep-sea remotely operated vehicles (ROVs): two ROVs worked more than 358 cumulative hours at 4,000 meters, with a single continuous operation lasting up to 103 hours. For the first time under IODP standards, scientists completed on-board core collection, cataloging, cutting, scanning, sampling, testing and archiving — capturing data before gases escaped and biological samples degraded.
Scientific Payoff: A Ridge Jump and Rich Organic Matter
The trial drilling was designed around a specific scientific target: the “spreading ridge jump” of the South China Sea. Spreading ridges form vast undersea mountain chains where magma erupts to create ocean crust; at roughly 50 locations worldwide, a ridge has “jumped” — spreading stops at one spot and resumes massively at another over one to two million years. The cause has long been debated but never tested by drilling.
Preliminary research confirmed that after the South China Sea spreading ridge jumped, multiple phases of large-scale volcanism occurred — key empirical evidence for core questions about how the basin formed and evolved. Sun said the evidence seems to indirectly support a hypothesized mantle-plume model, though “more analysis is needed to confirm.”
Two further finds stood out. The team discovered an alternation of oceanic red beds and green–dark-green sedimentary layers, which represent warm and cold climate periods respectively and are valuable for studying the region’s paleo-environment and modern climate change. They also encountered, at 813–864 meters below the seafloor, tens of meters of sand-mud interbedded deposits with clear bioturbation and rich organic matter.
“On the open ocean at 4,000 meters, the sediments are actually rich in organic matter — this far exceeded our imagination!” Sun said. It was the first time China found such features in the South China Sea in ultra-deep water more than 4,000 meters deep and far from land.
Background: From Paying Fees to Setting Records
The Mengxiang entered service in Guangzhou on November 17, 2024. The vessel is roughly 200 meters long and about 25 stories tall, with a maximum drilling depth of 11,000 meters — the strongest drilling capability of any ocean drilling ship. It carries nine onboard laboratories totaling more than 3,000 square meters and uses a “smart ship brain” drawing on more than 20,000 monitoring points, according to Science Net / Guangming Daily.
Before the Mengxiang, Chinese scientists had to pay steep fees — rising from US$500,000 to as much as US$3 million — to join international drilling voyages on foreign ships, and mostly followed others’ lead. The new ship aims to support global scientists in the long-held ambition of “drilling through the crust and reaching the upper mantle.”
What’s Next
The September voyage primarily tested China’s drilling capability and did not complete all scientific objectives. Sun said the team will return in 2027 for another voyage dedicated to completing the ridge-jump task. In the meantime, the recovered cores and data will be made available to researchers, feeding into a broader effort to understand how the South China Sea — and the planet’s deep interior — took shape.