The oceanographical expedition on board Hr. Ms. Willebrord Snellius spent 15 months in investigating the eastern part of the Netherlands East Indies from 1929 to 1930. The present author accompanied the expedition as geologist. The geological results of the expedition may be devided into two parts. The first comprises those subjects that stand in direct relationship to the oceanographical work of the expedition, viz: the geological interpretation of the bathymetrical data obtained, the geology of coral reefs and the bottomsamples. These subjects are to be dealt with in the reports of the expedition. Two volumes have already appeared: