The ocean basins cover the largest area of the Earth's surface. Because of plate tectonics, however, most oceanic lithosphere eventually is subducted. Thus the only existing oceanic lithosphere is younger than about Jurassic in age and occurs at locations farthest from the oceanic spreading centers. Except in areas where magmatism is intense enough to build volcanic structures above sea level, most of the oceanic magmatism is difficult to access. Samples of rocks can be obtained from drilling, dredging, and expeditions of small submarines to the ocean floor. Numerous samples have been recovered and studied using these methods. Most of the magmatism is basaltic. Still, few drilling expeditions have penetrated through the sediment cover and into the oceanic lithosphere.

The Integrated Ocean Drilling Program (IODP) is an international marine research program that explores Earth's history and structure recorded in seafloor sediments and rocks, and monitors subseafloor environments. IODP builds upon the earlier successes of the Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP), which revolutionized our view of Earth history and global processes through ocean basin exploration. IODP greatly expands the reach of these previous programs by using multiple drilling platforms, including riser, riserless, and mission-specific, to achieve its scientific goals.