The research priorities and drilling goals of the Ocean Drilling Program are introduced from two scientific themes. The scientific theme of the dynamics of the Earth's environment attempts to explain the Earth's changing climate, causes and effects of sea-level change, and other problems such as the global carbon cycle, formation of gas hydrates and submarine biological resources based on studies of sediment, fluids and bacteria. The scientific theme of the dynamics of the Earth's interior attempts to explore the transfer of heat and materials to and from the Earth's interior and to investigate deformation of the lithosphere and earthquake processes.