It's correct to use the definite article before the name of a river, canal, sea and ocean:
- When my father dies, we will have to wash him, wrap him in rich cloth, cremate him, and then sprinkle his ashes into the Ganges river.
- The terminal is located to the north-east of the Suez Canal.
- Land based pollution is relatively high in the Mediterranean compared to the other regional seas.
- Titanic is at the bottom of the Atlantic ocean.
However, we don't use an article before a lake:
- Look, this is Lake Victoria.
Why are lakes so special and different from rivers, canals, seas and oceans if it comes to the use of the article?