Underwater exploration is the exploration of any underwater environment, either by direct observation by the explorer, or by remote observation and measurement under the direction of the investigators. Systematic, targeted exploration is the most effective method to increase understanding of the ocean and other underwater regions, so they can be effectively managed, conserved, regulated, and their resources discovered, accessed, and used. Less than 10% of the ocean has been mapped in any detail, less has been visually observed, and the total diversity of life and distribution of populations is similarly obscure.
Types of exploration include investigation of the form and extent of the body of water or part thereof, investigation of the geological characteristics of the seabed and freshwater equivalents, and investigation of the geological structure, strata, and sediments underlying the body of water, investigation of the physical and ecological characteristics of the body of water and its containing geographical features, discovery and investigation of shipwrecks and archeological sites, and direct and remote visual observation of what is there.
The oceans can be divided into deep ocean and coastal waters. Inland waters are mostly fresh, and consist of rivers, lakes and ground water, some of which is in accessible caves.
Underwater exploration is largely a recent development, as it relies heavily on fairly advanced technology over almost all of the relevant territory.