Various technologies, exploratory vehicles and observation instruments are necessary to know and promote effective use of the oceans. JAMSTEC is almost unparalleled in the world in that JAMSTEC concurrently promotes oceanographic researches and development of various facilities for oceanographic observation. A number of JAMSTEC's highly evaluated technologies and means of observation are presented here. The sea, occupying about 70 percent of the earth's surface, has a great influence on the global environment. To learn more about the mechanisms of global warming and abnormal climates, detailed studies of the sea are necessary. JAMSTEC is conducting oceanographic surveys of the entire Pacific Ocean, including the tropical and arctic sea regions, being considered to have great influence on the climate. How accurately will we become able to forecast the global warming and abnormal climates? During the 1960s, a new outlook on the earth called "Plate tectonics" was established by the research of ocean floor. Now again, another new outlook on the earth is about to be born by deep-sea research and drilling of ocean floor, an international project in which JAMSTEC is a leading member. The ocean floor has secret keys to know the past, present, and future of the earth. About 90 percent of the earthquakes occurring in and around Japan have their epicenters below the seafloor. Great earthquakes and volcanic activities are caused by movement of earth's crust on the seafloor (oceanic plates). JAMSTEC investigates the seafloor where earthquakes can occur and conducts long-term observations of the oceanic plates. The forefronts of researches on great earthquakes and volcanic activities are introduced. In 1977 an ecological system hardly dependent on the solar energy was discovered around hydorthermal vents on seafloor off the Galapagos Islands. This discovery has revolutionized the concept of life. We have learned that a number of living organisms, having unique abilities, inhabit the deep-sea. JAMSTEC approaches deep-sea biospheres with its own ocean exploration and genome technologies. JAMSTEC is also developing technologies to make effective use of these microorganisms' abilities. One of the most important goals of the 21st century is to develop new resources and new energy sources. Methane hydrate resource on the seafloor, hydrothermal deposits, and sea wave energy are considered to be promising as future energy sources. JAMSTEC's technologies and efforts to utilize these resources are introduced.