2026 Cook Islands ROV Exploration
Dive 09: Southern Boundary Abyss
Location: Lat: -16.139428397°; -165.129706699°
Dive Depth Range: 5,596-5,607 meters (3.5-3.5 miles)
View dive images and videos
The ninth dive of the expedition took place on a rugged abyssal plain along the southern boundary of the Cook Islands’ exclusive economic zone (EEZ). The dive started at a depth of approximately 5,600 meters (3.5 miles) and traversed along a flat seafloor. As with all dives thus far on the cruise, we encountered polymetallic nodules on the seafloor. While the shape and size of the nodules on Dive 09 changed, we observed relatively dense nodule coverage throughout. Macrobiology was more prevalent, though not abundant, than previous dives as we encountered numerous sponges, sea cucumbers, polychaete worms, a few fish, a nudibranch, and even some snails. Shark teeth, likely from megalodon sharks given their size, were also abundant.
A highlight of the dive was a live interaction with Cook Islands Prime Minister, the Honorable Mark Brown. The science team of Dr. Aurora Elmore of NOAA, Dr. Amanda Demopoulos of the U.S. Geological Survey, and Tanga “TJ” Morris and Chloe Wragg with the Cook Islands Seabed Minerals Authority were able to talk about the work completed thus far on the cruise and plans for what is to come. During the interaction, Prime Minister Brown was able to guide remotely operated vehicle pilots in the collection of a very large shark tooth. NOAA Administrator Dr. Neil Jacobs issued a statement of partnership and a senior official from the U.S. Embassy in New Zealand also remotely joined the dive in support of scientific collaboration.
This was the last dive of the first leg of this cruise, with July 30, July 31, and August 1 being reserved for personnel exchanges and a transit to the northwestern boundary of the Cook Islands’ EEZ.
This cusk eel was seen swimming just above the rugged seafloor explored during the ninth dive of the 2026 Cook Islands ROV Exploration cruise. Despite their eel-like appearance, with long, thin bodies and bulbous heads, cusk eels are not true eels. Video courtesy of NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration. Download HD version (mp4, 33.6 MB)
This bristle worm was seen “dancing” in the water during Dive 09 of the 2026 Cook Islands ROV Exploration cruise. These polychaete worms have paired, bristle-like appendages called parapodia that extend outward from their body wall, giving them the appearance of a bristle brush, hence the common name. Video courtesy of NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration. Download HD version (mp4, 36.1 MB)
Several carnivorous sponges were observed while exploring the abyssal plain during Dive 09 of the 2026 Cook Islands ROV Exploration cruise. Carnivorous sponges use small hooks or barbs to capture prey such as small crustaceans floating in the water column. They are often found with anemone associates, which take advantage of the boost off the seafloor provided by the sponge, bringing the anemone closer to food in the water column. Video courtesy of NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration. Download HD version (mp4, 71.0 MB)
The team spotted a few sea cucumbers, also known as holothurians, during Dive 09 of the 2026 Cook Islands ROV Exploration cruise. Sea cucumbers are bottom feeders, using tube feet to move sediment from the seafloor to their mouths, extracting nutrients from the mud to gain energy. Their transparent bodies make it easy to see just what they ingested for their last meal. Video courtesy of NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration. Download HD version (mp4, 44.7 MB)
This brisingid sea star was seen feeding, with its arms extended into the water column during Dive 09 of the 2026 Cook Islands ROV Exploration cruise. While we get excited about glimpses of marine life during dives, overall biodiversity in deep waters of the Cook Islands is generally low due it being a very low-nutrient, or oligotrophic, environment. Video courtesy of NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration. Download HD version (mp4, 64.7 MB)
The 2026 Cook Islands ROV Exploration mission team, including (from left to right) Chloe Wragg and Tanga “TJ” Morris with the Cook Islands Seabed Minerals Authority, Dr. Aurora Elmore of NOAA, and Dr. Amanda Demopoulos of the U.S. Geological Survey, interact with Cook Islands Prime Minister Mark Brown during Dive 09 of the cruise. Image courtesy of NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration. Download largest version (jpg, 972 KB).
This carnivorous sponge was one of several seen during Dive 09 of the 2026 Cook Islands ROV Exploration cruise. Unlike filter feeding sponges, carnivorous sponges prey on animals such as small crustaceans that they capture from the water column. Image courtesy of NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration. Download largest version (jpg, 665 KB).
A dense field of polymetallic nodules greeted remotely operated vehicle Deep Discoverer at the start of Dive 09 of the 2026 Cook Islands ROV Exploration cruise. Image courtesy of NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration. Download largest version (jpg, 1.4 MB).
This cusk eel in the family Ophidiidae was seen during Dive 09 of the 2026 Cook Islands ROV Exploration cruise. Image courtesy of NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration. Download largest version (jpg, 717 KB).
This sea cucumber, or holothurian, was seen perched on polymetallic nodules during Dive 09 of the 2026 Cook Islands ROV Exploration cruise. Sea cucumbers are considered deposit feeders, feeding on nutrients attached to sediments on the seafloor. They use their modified tube feet to “eat” seafloor mud, extracting what little nutrition may have persisted after slowly sinking from the productive upper ocean, and then expelling undigested mud. The sea cucumber in this image has a rather full gut! Image courtesy of NOAA Ocean Exploration, 2026 Cook Islands ROV Exploration. Download largest version (jpg, 1 MB).