The sea trial of "KAIKO", the full ocean depth research ROV

Japan Marine Science and Technology center (JAMSTEC) developed a full ocean depth research ROV (remotely operated vehicle), "KAIKO", whose construction started in January, 1991, and whose sea trial was carried out from May, 1993 to March, 1995. The sea trial had three separated phases, that is, the first test at 1000 m deep ocean near the main land of Japan, the second test at Nansei Shoto Trench of 6500 m deep, and the final test at Mariana Trench in order to confirm the capability of the system at the deepest ocean bottom on Earth. The original plan for the final sea trial had been scheduled in July, 1993, however, it was delayed by some troubles. The main trouble was on the data transmission through a secondary cable between a launcher and a vehicle of "KAIKO". After clearing up all causes of the troubles, the authors carried out the sea trial again at Mariana Trench in March, 1995, and succeeded in the deepest challenge. This paper described the feature of "KAIKO" and the result of the sea trial.