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An examination of the oceanographic conditions in the region between Java and Australia during the south-east monsoon season shows that the main upwelling area in this region is situated along the coast of Java and Sumbawa, and not along the north-west Australian shelf, as was previously assumed. The amount of upwelling south of Java is estimated to contribute 2.4 million m3/sec to the South Equatorial Current and the upwelling velocity is of the order of 50 × 10-5 cm/sec. The region is characterized by very high concentrations of inorganic phosphate at the bottom of the euphotic layer and by a high plankton biomass. The transparency of the water in the upwelling area is low, indicating a high concentration of suspended matter. The possible development of the upwelling during the north-west monsoon season is discussed.

Geopotential topographies of the surface and several subsurface depths are drawn from observations on three cruises of H.M.A.S. Gascoyne in the waters of the western South Pacific Ocean in 1960 and 1961. The associated circulation is discussed. Surface circulation is found to be in agreement with the topographies only in the major current branches, while wind-induced currents do not show in the topographies. The inflow into the region occurs from the east between 25 S. and the Solomon Islands. It is stronger in subsurface layers than at the surface. A comparison with five cruises made by the Institut Franpais d'Oceanie in Noumea into the region between Kew Caledonia and the Solomons shows a permanent inflow in layers between 100 and 700 m, while the geostrophic circulation at the surface is very variable. The outflow from the region is effected by a current in the Tasman Sea between 30 and 36 S. flowing east and leaving the region north of New Zealand. Between Tasmania and New Zealand an outflow to the south occurs, reaching to 1200 m depth. The East Australian Current continues as an eddy system as far south as Tasmania. The calculated current pattern agrees in all parts with the circulation as derived from water mass analysis.

An analysis is made of subsurface water masses in the subtropical western South Pacific Ocean, using temperature-salinity and temperature-oxygen relations. Seven major water masses, characterized by extreme values of salinity and oxygen, are distinguished. These are the Subtropical Lower Water (salinity maximum), the upper oxygen minimum, the Subantarctic Intermediate Water (oxygen maximum), the Antarctic Intermediate Water (salinity minimum and oxygen maximum), the deep oxygen minimum, the Deep Water (salinity maximum), and the Bottom Water. The core layer method is used to describe the distribution of the different water masses and to draw conclusions on their spreading.

Geopotential topographies of the surface and several subsurface depths are drawn from the observations on three cruises of H.M.A.S. Diamantina in the waters to the west and south of Australia in 1959 and 1960. The associated circulation is discussed. Surface circulation is found to be in general agreement with the observed surface currents. The subsurface flow between 300 and 1200 m depth indicates an entry of water from the south across 32 S. which turns to the west south of 20 S. Transports in certain current systems and eddies are calculated. The importance of internal waves in the south-west of the region, having amplitudes of more than 100 m, is discussed.

The hydrographic conditions in the deep sea basins of the western South Pacific Ocean are analysed using relations between potential temperature and salinity, based on observations made from H.M.A.S. Gascoyne in 1960. It is shown that the bottom waters in the Coral Sea Basin and in the Solomon Basin are both characterized by a comparatively high salinity and that they come from the East Australian Basin. The bottom waters in the New Hebrides Basin, the New Caledonia Trough, and the Fiji Basin come from the central Pacific Basin. The water in the New Hebrides Basin and that in the New Caledonia Trough both have a slight admixture of water of higher salinity which has escaped over the ridges on the east sides of the Coral Sea Basin and the Solomon Basin. The Coral Sea Basin and the Solomon Basin considered as a unit is an example, probably the unique case, of . the inflow into a basin occurring at a higher level than the outflow. The sill depths of the different basins are determined by using potential temperature characteristics. The water exchange of the Coral Sea Basin is discussed theoretically. The upward velocity at depths between 3000 and 4000 m is of the order of 1.5 × 10-5 cm/sec and the rate of inflow 0.04 million m3/sec.