Nearly two million square kilometres of ocean surround the Cook Islands, yet much of the seafloor remains among the least explored places on Earth. While satellites have transformed our understanding of the planet from above, the deep Pacific Ocean continues to conceal landscapes, ecosystems, and geological formations that have rarely, if ever, been seen by human eyes. Throughout July and August 2026, NOAA Ocean Exploration, in partnership with the Cook Islands Seabed Minerals Authority (SBMA) and a broad coalition of scientific organisations, is working to change that through the 2026 Cook Islands ROV Exploration aboard NOAA Ship Okeanos Explorer.
Running from 19 July to 13 August 2026, the 26-day expedition is dedicated to expanding scientific understanding of the Cook Islands’ deep ocean by combining high-resolution seafloor mapping, remotely operated vehicle (ROV) dives, water-column observations, and geological and biological investigations. Rather than focusing on commercial activity, the mission aims to establish baseline scientific knowledge that will support future research and evidence-based management of one of the world’s largest and least explored exclusive economic zones.
The Cook Islands comprise just fifteen islands, yet they are surrounded by almost 2 million square kilometres of ocean. Beneath these waters lies an extraordinary underwater landscape where the average depth approaches 5,000 metres and, across much of the region, the seafloor extends beyond 2,500 metres. Hidden beneath the surface are seamounts, abyssal plains, and sections of the vast Manihiki Plateau, environments that remain scientifically understudied despite their ecological and geological significance.
To better understand these remote habitats, Okeanos Explorer employs advanced multibeam sonar systems capable of producing detailed maps of the seafloor, water column, and underlying geological structures. These surveys reveal underwater features with remarkable precision while identifying locations for subsequent ROV investigations. Every newly mapped section contributes to a growing understanding of the Cook Islands’ marine environment, helping scientists identify previously unknown features, refine geological interpretations, and establish a stronger foundation for future ocean research.
Among the expedition’s most important technologies are the remotely operated vehicles Deep Discoverer and Seirios. Operating thousands of metres beneath the ocean’s surface, these robotic systems allow scientists to observe the deep sea in real time while remaining safely aboard the research vessel. Equipped with high-definition cameras, precision lighting, navigation systems, and scientific sampling equipment, the vehicles provide unprecedented access to environments that are otherwise beyond the reach of conventional diving.
ROV dives throughout the expedition are expected to reach depths between approximately 2,500 and 6,000 metres, traversing seamounts, abyssal plains, and plateau features to document geology, biodiversity, and environmental conditions. Every descent offers opportunities to observe organisms that have adapted to crushing pressure, near-freezing temperatures, and complete darkness, while simultaneously recording geological processes that have shaped the Pacific Ocean over millions of years.
As the vehicle settles onto the seabed, the landscape transforms into a world few people have ever witnessed. Vast plains covered in polymetallic nodules stretch across the ocean floor, interrupted by rocky outcrops, isolated geological formations, and communities of deep-sea organisms uniquely adapted to one of Earth’s most extreme environments. Scientists carefully document these habitats through continuous video observations while recording the distribution of species across different geological settings.
The expedition’s biological investigations extend far beyond simply identifying marine life. By documenting the diversity and distribution of animals inhabiting seamounts, abyssal plains, and plateau environments, researchers hope to better understand how deep-sea communities vary across the Cook Islands’ underwater landscapes. These observations contribute to long-term scientific knowledge of biodiversity, ecosystem resilience, and the environmental conditions that shape life in the deep Pacific.
One of the expedition’s remarkable observations includes members of the family Psychropotidae, commonly known as deep-sea swimming sea cucumbers. These delicate, translucent animals drift across the abyssal zone, demonstrating the extraordinary adaptations that enable life to thrive thousands of metres beneath the surface.
Geological investigations are equally important throughout the mission. Scientists are studying seafloor features, sediment composition, and the geological history of the Cook Islands while collecting carefully selected samples that provide additional context to the visual observations made during each dive. During Dive 01, the expedition successfully tested the collection of a push core using Deep Discoverer, enabling researchers to recover intact sediment samples from the seafloor for detailed laboratory analysis. These cores preserve valuable records of geological and environmental processes that have unfolded over thousands, and in some cases millions, of years.
Another notable discovery has been the recovery of a fossilized shark tooth coated in ferromanganese oxide. Such specimens provide important insights into the long-term geological processes occurring on the abyssal seafloor while highlighting the extraordinary timescales over which minerals accumulate within these remote marine environments.
Complementing the ROV operations are extensive water-column investigations using conductivity, temperature and depth (CTD) systems, acoustic Doppler current profilers, expendable bathythermograph probes, Argo floats, and collected water samples. Together, these instruments allow researchers to build a comprehensive picture of physical, chemical, and biological conditions throughout the water column, helping improve understanding of ocean circulation, marine ecosystems, and the environmental processes influencing the region.
One of the defining features of the expedition is its commitment to open science. Through NOAA Ocean Exploration’s telepresence technology, scientists from around the world can participate remotely while members of the public are invited to watch many of the dives live online. This real-time access allows researchers across multiple disciplines to contribute observations and interpretations as exploration unfolds, extending scientific collaboration far beyond the research vessel itself.
The expedition also reflects a close partnership between NOAA Ocean Exploration, the Cook Islands Seabed Minerals Authority, the U.S. Geological Survey, the Ocean Exploration Cooperative Institute, the U.S. Department of State, and numerous scientific specialists working together to better understand the Cook Islands’ deep-ocean environments. Importantly, the cruise is a scientific exploration and mapping initiative designed to support the Cook Islands’ understanding of its marine environment. It does not authorise commercial seabed minerals harvesting, nor does it replace Cook Islands law, public consultation processes, or existing environmental safeguards. Instead, the scientific data collected during the expedition will help provide an evidence-based foundation for future decision-making while remaining publicly accessible through NOAA’s data archives after the mission concludes.
On 5 August 2026, the expedition’s Dive 11, known as Northern Border Abyss 2, targeted an abyssal site in the northern portion of the Cook Islands Exclusive Economic Zone at an approximate starting depth of 5,400 metres. Scientists focused on documenting both the geological characteristics and biological communities present within this priority area, continuing the expedition’s broader objective of improving understanding of one of the deepest and least explored regions of the Pacific Ocean.
As Okeanos Explorer continues its work across the Cook Islands, every sonar survey, every remotely operated vehicle dive, and every scientific observation contributes another piece to a much larger puzzle. From mapping hidden landscapes and documenting extraordinary deep-sea organisms to investigating ancient geological formations and expanding knowledge of the ocean itself, the 2026 Cook Islands ROV Exploration serves as a reminder that some of Earth’s greatest frontiers remain beneath the waves. Through international collaboration, advanced technology, and a commitment to openly shared science, this expedition is not only revealing the Pacific’s hidden depths but also laying the foundation for a deeper understanding of one of the planet’s last great unexplored environments.
