The ocean, unlike the globally enveloping atmosphere is segmented into seas, interconnected with passages of varied dimensions. Each ocean differs somewhat in its overall temperature and salinity, which owing to the great heat capacity of seawater and its central role in the hydrological cycle exert a strong influence on climate. The Pacific is relatively cool and fresh, well stratified, while the Atlantic is warm and salty, prone to deep reaching overturning circulation in the northern North Atlantic, which among other consequences leads to a rather warm amiable climate of northern Europe.

A truly unique part of the ocean's geography is the seas of Southeast Asia, with such exotic names as the Java Sea, the Sulu Sea and the South China Sea. What makes these seas so fascinating to the oceanographer is their archipelago arrangement, stretching some 2800 miles from Australia to southeast Asia. The multitude of Islands of the Philippines and Indonesia constrain the ocean into a configuration of narrow passages and seas, of varied sizes and depths. Archipelago arrangement represents a challenge to our understanding of ocean processes, as needed to properly simulate the ocean and climate models. Yet we need to get it right, as through these southeast Asian seas tropical Pacific water weaves its way into the Indian Ocean, in what is referred to as the Indonesian Throughflow (ITF), which affects the characteristics of such well known climate phenomena as El Niño and the Asian monsoon.

Lamont oceanographers are involved in many field studies of the Indonesian and Philippine Seas: 1. The "International Nusantara Stratification and Transport" (INSTANT) program in the Indonesian Seas, presently in its data analysis phase; 2. on-going monitoring of the Makassar Strait throughflow, the primary conduit of the Indonesian Throughflow; 3. Study of the throughflow from the South China Sea to the Java Sea via the Karimata Strait; and 4. the "Characterization and Modeling of Archipelago Strait Dynamics" (PhilEx) in the Philippine Seas.