In the summer of 1976, the R/V THOMAS WASHINGTON of the Scripps Institution of Oceanography carried out a series of geophysical, geological, and physical oceanographic programs in the marginal basins between the Pacific Ocean and Asia, on legs 4 through 8 of INDOPAC Expedition. Work was in the Philippine, South China, Sulu, Celebes, Molucca, Banda, and Arafura Seas. This report includes chronology of work, cruise tracks, lists of samples, stations, and observations, and some preliminary results. Among the significant preliminary results were the sampling of metamorphic rocks along the Yap island arc; the observation of anomalous crustal structure beneath the Philippine Sea and the Okinawa Trough; measurement of about 10 km of melange material in the Molucca Sea, which at the edges thrusts up over the arcs on either side of the Molucca Sea; observation of continental crust beneath the Timor-Tanimbar-Aru troughs. A turbidity current was recorded by current meters off the Abra delta of Luzon. Strong south-flowing currents were recorded showing transport of water through Lifamatola Strait from the Pacific to the Indian Ocean. Work on leg 5 was in cooperation with the R/V CHIU LIEN of National Taiwan University; work on leg 8 was in cooperation with the R/V ATLANTIS II of Woods Hole Oceanographic Institution.

In the first half of 1977, the R/V Thomas Washington of the Scripps Institution of Oceanography continued work on INDOPAC Expedition, starting from Guam, Marianas, and ending in San Diego. Geophysical and geological programs were carried out in the marginal seas of southeast Asia; biological and physical oceanographic programs were carried out near Guam, and in the central and eastern Pacific. This report includes a brief summary of the work on each cruise leg, a chronology, cruise tracks, and lists of stations, samples, and observations. Work on leg 13 was in cooperation with the K/M Samudera of the Indonesian Institute of Sciences.