Exploration of the Marshall Islands with the Ocean Exploration Trust

Between July 27 and August 17, the Ocean Exploration Trust and partners carried out a 21-day telepresence-enabled expedition to explore deep-sea habitats surrounding the Marshall Islands. Using Nautilus’ remotely operated vehicle (ROV), mapping tools, and telepresence systems, we surveyed sites around the Marshall Islands.

Throughout the planning and execution phases, the expedition team collaborated closely with stakeholders in the Marshall Islands to ensure the mission aligned with local priorities in science, resource management, and education. Three Marshall Islands-based scientists joined the expedition onboard, while additional participants contributed remotely from shore.
The expedition successfully completed ten remotely operated vehicle (ROV) dives, totaling 106 hours of dive time and 74 hours of active seafloor exploration. This included one brief test dive near Honiara and nine operational dives across deep-sea habitats in the Marshall Islands, ranging from depths of 953 to 3,326 meters. The dives focused on ecologically significant environments, particularly offshore seamounts and slope habitats.

Notable discoveries included vibrant and diverse deep-sea coral and sponge communities on two seamounts within the National Marine Sanctuary of Bikar and Bokak. The team documented extensive coral gardens on steep vertical relief and identified at least two new species of octocorals, along with several invertebrate records previously unreported in the Marshall Islands.

In addition to standard sensors, ROV Hercules was equipped with an autonomous environmental DNA (eDNA) sampler. This system filtered over 20,000 liters of seawater at depth, resulting in the collection of 161 eDNA samples. The expedition also gathered 77 biological specimens and 30 rock samples to support research on biodiversity, coral reproduction, biogeography, and regional geology.