It is the study of ocean plants and animals and their ecological relationships. The study of Marine Biology includes astronomy, physical oceanography, geology, botany, genetics etc.
Advances in technology have opened up the ocean to exploration from the shallows to the deep sea. New tools for marine research are being added to the list of tools that have been used for decades such as Trawling, Plankton nets, Remotely operated vehicles, Underwater habitats etc.
The study of marine biology also follows the scientific method. The overriding goal in all of science is to find the truth.