- In March, Mongabay’s Elizabeth Claire Alberts and CNN International’s Kara Fox co-published an investigation into China’s deep-sea mining fleet’s ambitions and the alleged military dual uses of its oceanographic research ships. This project was supported by the Pulitzer Center, where Alberts was a 2024-2025 Ocean Reporting Network fellow.
- A key finding was that eight Chinese ships involved in deep-sea mining research only spent about 6% of their sea time over the last five years in internationally designated seabed mining areas, while spending the rest of the time elsewhere, including areas identified by Western experts as strategically important for military reasons.
- The investigation illustrates that the nascent deep-sea mining industry not only poses potential environmental risks, but also presents geopolitical implications.
- This article explains how Alberts and Fox worked together to undertake this investigation, which has drawn international attention and was cited or republished by outlets including The New York Times, Inkstick Media and Island Business.
A version of this story was originally published by the Pulitzer Center, which supported Elizabeth Claire Alberts as an Ocean Reporting Network fellow.
We didn’t set out to investigate China’s deep-sea mining fleet, but as our research into the burgeoning industry developed over our yearlong partnership, it became clear that an investigation into the fleet’s alleged military dual use was emerging as an important, untold story.
Shortly after we embarked on our joint project, geopolitics around the deep-sea mining landscape began to shift dramatically. In February 2025, China signed an agreement with the Cook Islands government to collaborate on deep-sea mining research and exploration. At the same time, it was pursuing a similar deal with the archipelago nation of Kiribati, marking a notable expansion of Chinese influence in the Pacific.
China holds the largest number of exploration contracts issued by the International Seabed Authority (ISA), the U.N.-affiliated deep-sea mining regulator, and is also its biggest financial contributor. It also operates the world’s largest oceanographic research fleet. Against this backdrop, we kept returning to a central question: was China’s pursuit of deep-sea mining driven solely for accessing mineral resources, or was it also shaped by broader geopolitical strategy? Through extensive reporting, we learned that China’s interest in seabed mining was motivated by both of these things, and that some of its vessels were engaged in both deep-sea mining work and militarily strategic surveillance.
Meanwhile, deep-sea mining efforts have been gathering pace in the United States. In March 2025, The Metals Company, a Canadian company, announced its intention to file a mining application in the U.S., despite already holding an exploration license with the ISA. Critics argue that such a move would violate international law and constitute a breach of obligations to the ISA. A month later, the Trump administration issued an executive order calling for the U.S. to unilaterally accelerate its deep-sea mining plans in both national and international waters, citing as one of its main reasons the need to “counter China’s growing influence over seabed mineral resources.”
Navigating the data
Working as a collaborative team, we merged our distinct expertise to uncover this complex maritime story.
Together, we analyzed five years of MarineTraffic shipping data, submitted public records and freedom of information requests, and established relationships with experts who provided crucial feedback. Backed by data editors from our news organizations and the invaluable help of the research and data team at the Pulitzer Center, we transformed raw data and expert reviews into a comprehensive, verified investigation.
We started with what was already in the public domain, engaging with experts who had written about the alleged dual nature of China’s oceanographic fleet. This included Darshana Baruah of Indo-Pacific Defence and Strategy at IISS–Asia in Singapore; Liselotte Odgaard of the Washington, D.C.-based Hudson Institute; and Pooja Bhatt of the Jindal School of International Affairs in India. We also engaged with researchers from the Washington-based Center for Strategic and International Studies (CSIS), whose foundational work on the military dual use of China’s oceanographic fleet in the Indian Ocean in 2024 provided valuable insights. Their expertise also helped us hone our approach for this investigation.
Next, we needed to identify China’s vessels involved in deep-sea mining research. We did this by looking at ownership information from Chinese deep-sea mining companies, state media and Chinese news sources, and a recent publication by Ryan D. Martinson of the U.S. Naval War College’s China Maritime Studies Institute. There are more than 40 ships in China’s deep-sea mining research fleet. Through our reporting, we landed on a list of eight vessels, based on data showing they had spent time in ISA exploration sites contracted to Chinese companies (and one reserve area designated by a Chinese company to the ISA) over the past five years.
We analyzed five years of vessel-tracking data from MarineTraffic, a global maritime intelligence platform, to identify these vessels’ voyaging patterns and any activity that suggested unusual activity to further investigate.
We focused on the following criteria for our analysis:
- Visits to known Chinese military ports;
- Voyages and loitering in other countries’ exclusive economic zones (EEZs);
- Periods when vessels turned off automatic identification system (AIS) tracking, a radio signal with identification and location data that larger vessels are supposed to broadcast when at sea.
We used QGIS, a geographical data visualization and analysis tool, to map out our initial data points, and also accessed vessel tracking data on the newly launched Deep Sea Mining Watch platform, which provided a user-friendly interface to support our own work.
This vessel tracking data revealed several notable insights.
Over the past five years, these eight vessels spent a combined 814 days operating in or near areas licensed or reserved for exploration by the ISA, underscoring China’s strong interest in deep-sea mining. At the same time, the data led to a key finding in our investigation: only about 6.4% of the vessels’ total operating time was spent within ISA-designated exploration zones. The vast majority of their activity occurred outside these areas.
But what were these ships doing in other parts of the ocean?
We identified activity that appeared to be worth investigating, such as a vessel lingering in another country’s EEZ or appearing to disable its AIS, the mandatory, automated maritime transponder tracking system. These are referred to as AIS-off events. We cross-referenced those timings with any news or developments that might already be in the public domain, looking for information in local media or from reputable local analysts to gain more clues.
We also took a selection of routes, movements and AIS-off events to more than a dozen naval, civil and academic analysts, showing them the maps, including some in real time, so they could verify what we had identified and provide additional context and insight into the routes’ significance.
For data on the AIS-off events and movement near undersea cables, we obtained additional data support from Starboard Maritime Intelligence, a platform used by government agencies, defense forces and critical infrastructure operators.
At the same time, maintaining a strong focus on the environmental implications of the deep-sea mining industry was essential to our story, particularly for the readers at Mongabay. We drew on existing scientific research and interviews with environmental experts, who outlined potential impacts on both the seabed and the wider marine environment, some of which could be long-lasting or irreversible. This included sonar that affects whales, and risks to little-known species deep in the ocean.
Lessons from the voyage
Ultimately, distinguishing whether Chinese vessels are conducting scientific research or gathering military intelligence relies on expert interpretation of the data. To back up our findings, we took our reporting to our various experts, sometimes many times, to check and recheck. We were sure to seek any insights that might challenge our thesis.
One of the most important parts of our work was taking preliminary findings to multiple subject-matter experts to fact-check data and uncover new leads.
At times, our experts offered conflicting interpretations of the data, so we would return to the drawing board to reevaluate, remembering that it is far better to have a finding challenged — or even dropped — at the prepublication stage than to face a correction later.
We found that if a lead was shrouded in conflicting opinions, we should walk away from it altogether.
We also engaged experts during the hypothesis stage to build rapport and set the tone for our investigation. By the time we had specific data points to highlight, our sources were already invested in the project, with many proving incredibly helpful in providing deep-dive feedback.
We sought a global and multidisciplinary panel, consulting more than a dozen experts across several continents, balancing naval intelligence with academic rigor to ensure a 360-degree view. But one limitation was that we couldn’t include everyone in the final copy. We struggled with this, as all of our experts had such rich and important perspectives to bring, but we were ultimately bound by the limitations of space.
We also acknowledged that we didn’t need to be data scientists to produce data-driven journalism; the collaboration on this story was key. We partnered with colleagues in both of our newsrooms who were able to support our technical needs and who helped with mentoring on some steps throughout the process.
While we used QGIS after training with the Pulitzer Center’s data team, tools like the Deep Sea Mining Watch platform, as well as Kpler’s MarineTraffic and Google Earth also offered powerful, accessible alternatives.
Working as a collaborative team
We were introduced through one of Elizabeth’s colleagues, Erik Hoffner, Mongabay’s impact editor, who had met Kara at a Society of Environmental Journalists (SEJ) conference in Philadelphia in 2024, during her Ted Scripps Fellowship in Environmental Journalism. After an initial call, we quickly decided that we wanted to work together, driven by a shared interest in telling stories about deep-sea mining. At the same time, we recognized that CNN and Mongabay are very different platforms, and that a single, identical story may not necessarily work for both.
While our published pieces ended up being similar, we worked toward what was most appropriate for our respective platforms and audiences. The CNN story took a deeper dive into the geopolitics, particularly surrounding China’s vessel movements in the South China Sea. Mongabay devoted more attention to China’s overall role in deep-sea mining, analyzing vessel activity in mining zones, highlighting the extent of Chinese exploration areas, and expanding on the environmental stakes.
Our two stories also presented this work differently, with CNN’s production a visually rich, highly interactive feature, and Mongabay’s incorporating beautifully designed static graphics throughout, with some interactivity focused on one of the vessels.
Working collaboratively came with its challenges, especially when balancing the demands of our respective newsrooms, but what carried the project through was clear and consistent communication, mutual respect for each other’s work, and a shared determination to see the project to completion. It also helped that we genuinely enjoyed working together.
Banner image: Model of Jiaolong, one of China’s biggest manned submersibles, at the Five-Year Achievements Exhibition. Image by N509FZ via Wikimedia Commons (CC BY-SA 4.0).
The original investigation was co-published on Mongabay and CNN International.
Elizabeth Claire Alberts is a senior staff writer for Mongabay and was a 2024-2025 fellow with the Pulitzer Center’s Ocean Reporting Network. Find her on Bluesky and LinkedIn.
Kara Fox is a senior reporter at CNN International and a guest contributor to the Pulitzer Center.
