ABISMO

Lore & Background

Development of ABISMO began in April 2005, after the temporary replacement ROV Kaikō7000II—rated only to 7,000 meters—could not reach the deepest oceanic trenches. Like its predecessor Kaikō, ABISMO consists of four major parts: electronic instruments aboard the support ship RV Kairei, a launcher, a vehicle, and samplers. The launcher houses the vehicle in a stainless steel framework, with pressure hulls, a winch, a secondary cable drum, and electric transformers in its upper part. The vehicle is hung in the launcher by a docking system; when detached, the cable drum feeds the secondary cable, allowing the vehicle to dive while its position is measured by an acoustic positioning system. The launcher also carries a high-definition television camera with pan and tilt functions.

Initial sea trials were conducted in 2007, during which ABISMO successfully reached a planned depth of 9,760 meters in the Izu–Ogasawara Trench and collected core sediment samples. In June 2008, during cruise KR08-05 Leg 1, dives 11–13 almost reached the bottom about 150 km east of the Challenger Deep, but the legacy primary cable of the Kaikō system was too short; a gravity core sampler was dropped in free fall, obtaining 1.6 m of sediment. Dive #14 explored the TOTO caldera, capturing video of a hydrothermal plume. Upon successful testing to 10,000 meters, ABISMO became briefly the only full-ocean-depth-rated ROV in existence. On 31 May 2009, it was joined by Woods Hole's HROV Nereus as the only two operational full-ocean-depth capable ROVs. During its deepest sea trials dive, a manometer measured 10,257 m ±3 m in an area near 12°43' N, 143°33' E.

Reader's Guide

ABISMO's significance lies in its role as the sole remaining ROV capable of reaching 11,000 meters after the loss of Nereus in 2014. It serves as the permanent replacement for Kaikō, which was lost in 2003, and continues the deep-sea exploration mission of JAMSTEC. Supported by RV Kairei, ABISMO conducts surveys and observations of oceanic plateaus, abyssal plains, oceanic basins, submarine volcanoes, hydrothermal vents, oceanic trenches, and other underwater terrain features to a maximum depth of 11,000 meters. Its launcher system, similar to Kaikō's, enables sediment sampling via gravity corer or bottom grab sampler, and its acoustic positioning system allows precise navigation. The vehicle's successful tests to 10,257 meters and its collection of sediment and water samples demonstrate its operational capability. ABISMO's legacy is tied to the continuity of full-ocean-depth ROV research, filling the gap left by Kaikō and Nereus, and enabling ongoing exploration of the deepest parts of the ocean.

Did You Know?

• Its deepest measured depth during sea trials was 10,257 m ±3 m.
• The project name ABISMO translates to 'abyss' in Spanish and Portuguese.

Sole Guardian of the Deepest Trenches

ABISMO occupies a singular position in the global fleet of deep-sea research vehicles. After the Woods Hole Oceanographic Institution's Nereus was lost at sea in 2014, ABISMO became the sole remaining remotely operated vehicle on Earth rated to operate at 11,000 meters. Before that, it shared that distinction with Nereus, which joined it in May 2009. ABISMO was conceived as the permanent successor to Kaikō, JAMSTEC's earlier 11,000-meter-class ROV that was lost off Shikoku Island in May 2003 when a steel secondary cable snapped during Typhoon Chan-Hom. In the interim, JAMSTEC relied on Kaikō7000II, a converted vehicle rated only to 7,000 meters, which could not reach the deepest oceanic trenches. ABISMO's existence therefore represents not merely a technological upgrade but the preservation of humanity's capability to directly observe and sample the very bottom of the ocean's deepest trenches.

System Architecture and Operational Design

ABISMO follows the same four-component architecture as its predecessor Kaikō: electronic instruments aboard the support ship, a launcher that doubles as a sampling station, the vehicle itself (described as a sediment probe), and dedicated samplers. The launcher's lower section is a stainless steel framework that houses the vehicle, while its upper section holds pressure hulls for electronics, a winch, a secondary cable drum, and two electric transformers. Two types of samplers are included—a gravity core sampler and a bottom grab sampler. The vehicle hangs from a docking system inside the launcher; once detached, the cable drum feeds the secondary cable and the vehicle descends, with its position tracked by an acoustic positioning system while the launcher's position is monitored from RV Kairei. An HDTV camera with pan and tilt capability is mounted on the launcher. The overall system is smaller than Kaikō's, but the fundamental configuration remains the same.

Milestone Dives and the Path to Full-Ocean-Depth Certification

ABISMO's initial sea trials took place in 2007, when it reached a planned depth of 9,760 meters in the Izu-Ogasawara Trench and collected sediment core samples from the seabed. In June 2008, JAMSTEC deployed the 4,517-ton RV Kairei to waters near Guam for cruise KR08-05. During Leg 1 (June 1–3), dives 11 through 13 targeted the area roughly 150 km east of Challenger Deep but fell short of the seafloor because the legacy primary cable from the Kaikō system proved slightly too short; a 2-meter gravity core sampler was released in free fall, yielding 1.6 meters of sediment, and twelve water samples were collected at various depths. Dive 14 entered the TOTO caldera, capturing video of a hydrothermal plume. Upon successful testing to 10,000 meters, ABISMO briefly became the only full-ocean-depth-rated ROV in existence. Its deepest trial dive recorded a manometer reading of 10,257 meters ±3 meters near 12°43'N, 143°33'E.

The Kairei Platform and Broader Research Mission

ABISMO does not operate in isolation; it is tethered to the Deep Sea Research Vessel Kairei, a 4,517-ton support ship that previously served Kaikō and the interim Kaikō7000II. Together, they conduct surveys and observations of oceanic plateaus, abyssal plains, oceanic basins, submarine volcanoes, hydrothermal vents, oceanic trenches, and other underwater terrain features down to 11,000 meters. Kairei also carries a multi-channel reflection survey system for probing the structure of deep sub-bottoms with complex geometries in subduction zones. The vessel's operational history is inseparable from ABISMO's development: it supported the 2008 Guam cruises, including Leg 2 under chief scientist Takashi Murashima, which tested JAMSTEC's Free Fall Mooring System—a lander successfully deployed twice to 10,895 meters in the central basin of Challenger Deep, where it captured video and sediment samples at 11°22.14'N, 142°25.76'E. The ship thus anchors an entire ecosystem of deep-sea research capability.