Exploration survey cruise of manganese nodule in the Clarion-Clipperton Zone (CCZ) has been conducted by DOMA (Deep Ocean Minerals Association) and DORD (Deep Ocean Resources Development Co., Ltd.) from 1975 to 1996 and 2011 to present. The manganese nodule survey of Japan in the CCZ during these periods is reviewed in this paper. From 1975 to 1987, the surveys were conducted in a wide area of the CCZ (3 million km2) in order to find and extract high potential areas of manganese nodules. After the registration of the Japanese license area (75,000km2, consisting of West Area and East Area) in 1987, the aims of the surveys were shifted toward building up exploration techniques during 1987 to 1996, rather than extraction of high potential area. From 2011, exploration works were carried out in a selected area of the High Abundance Area (HAA), located in northwest of the West Area, for the purpose of increasing accuracy of manganese nodule resources by additional sampling, seafloor observation with taking photographs and acoustic sounding survey. Most of the area of the HAA, which is selected as a possible first target for commercial mining of Japan in future, is covered by the area of high nodule abundance of more than 10 kg/m2. For the survey of 2012 in the HAA, AUV (Autonomous Underwater Vehicle) equipped with MBES, SBP, SSS and deep seas camera was used. Exploration equipment of modern technology such as AUV plays indispensable role in deep sea survey, and it is highly important to keep up with updated technologies for increasing quality of the surveys. Furthermore, the selection of model area(s) and the determination of the priority of survey contents are necessary for the preparation of the future survey plan.
