Environments in which you can find water are called aquatic environments. There are two main categories of aquatic environments- marine (oceans and seas) and freshwater (rivers, streams, ponds, etc.).
Oceans are a type of marine aquatic environment. Oceans are the largest ecosystem on Earth. The lifeforms that live within the ocean is dependent on the depth of water.
Coral reefs are also a form of marine aquatic environment. Coral reefs host many photosynthesizing algae. The reefs feed on these algae and grow. In turn, coral reefs are habitats for many fish.
Lakes and ponds are examples of freshwater aquatic ecosystems. The volume and surface areas of lakes and ponds varies greatly. Lakes are ponds are defined as freshwater environments that lack the movement of water.
The following links provide more information on each of the environments listed above.