Articles with geographical names

Will we use the definite article “the” or zero article before rivers?

Will we use the definite article “the” or zero article before group of mountains?

Will we use the definite article “the” or zero article before a mountaintop?

Will we use the definite article “the” or zero article before deserts?

Will we use the definite article “the” or zero article before continents?

Will we use the definite article “the” or zero article before towns?

Will we use the definite article “the” or zero article before countries whose name includes a word like REPUBLIC OR UNITED?

Will we use the definite article “the” or zero article before group of lakes?

Will we use the definite article “the” or zero article before oceans?

Will we use the definite article “the” or zero article before groups of islands?