The Australian Territory of Christmas Island, a raised atoll with a population of about 2000 people, lies on oceanic crust about 1600 km north- north west of Australia's Northwest Cape, and 350 km south of western most Java (Fig. 1). The Australian Cocos-Keeling Islands group is 1000 km further west. Christmas Island resembles a 'T', with its stem running east-west (Fig. 4), has an area of 140 km2, and is up to 20 km across. Australia has declared a 200 mile fisheries zone around Christmas Island. The island is on the Indo-Australian Plate, which is moving 'north at about 7cm/year, and is being uplifted on the bulge in front of the Java Trench 150km to the north. It has the form of a plateau at 200-300 m above sea level,bounded by a series of sea cliffs and terraces. The plateau slopes to the south; the highest point is Murray's Hill (361 m) on the western end of the island. The natural vegetation is tropical rain forest. The island is at the eastern end of the submarine Christmas Rise, which extends south-south west for 700 km (Fig. 1). The Java Trench to the north is more than 6500 m deep, and the abyssal plains around the Christmas Rise are 5000-6000 m deep. The rise sits on oceanic crust of presumed LateCretaceous age, and both it and the pedestal of the island consist largely of volcanics. On the island the volcanics are overlain by Eocene limestone, and an extensive Miocene limestone which is associated with extensive phosphate deposits. These deposits produced nearly 1,000,000 tonnes a year of phosphate rock until 1987 when mining ceased. Mining resumed at asmaller scale in 1991. In early 1991, the Australian Department of Foreign Affairs and Trade requested BMR to undertake a study of the non-living seabed resources of the area around Christmas Island, as an aid to seabed boundary delimitation negotiations. This work arose from the request, and started in January 1992, using RV. Rig Seismic. A cruise narrative is provided in Appendix 7