Surface water refers to water that is on Earth’s surface (ie excluding groundwater and atmospheric water). Surface water includes oceans, seas, lakes, rivers, ponds, wetlands and marshes.
Use initial capitals for the formal names of surface water bodies:
Pacific Ocean Murray River Piccaninnie Ponds Karst Wetlands
Use lower case for generic references to surface water:
the bay river systems of the Murray–Darling Basin
Reminder. Initial capitals are used only for formal names. Informal and collective (plural) references to the same item do not need capitals.
Use initial capitals for named drainage divisions and river regions:
South West Coast drainage division Denmark River
Seafloor features have initial capitals if they are formal names; otherwise, use lower case:
Great Barrier Reef Mariana Trench Cape Horn Seamount Gascoyne Abyssal Plain Challenger Deep seafloor
Use lower case for generic and plural terms:
trench continental shelf reef the Ashmore and Cartier reefs
See also:
