Rule 1 – ‘The’ is used for geographical points on the globe.
Example: The north pole and the south pole can never meet.

Rule 2 – ‘The’ is used for the nouns that cannot be counted.
Example: The water in the Pacific ocean is freezing.

Rule 3 – ‘The’ is used with geographical nouns, depending on the size and plurality of the noun. ‘The’ must precede the names of oceans, rivers, group of islands, lakes, mountains, countries with united states or islands, etc.
Example: The Ganga is a holy river.