When Should You Capitalize Oceans, Mountains, Lakes, and Other Geographic Features?

Is Colorado home to the Rocky Mountains or the Rocky mountains? Is the United States flanked by the Atlantic and Pacific Oceans or the Atlantic and Pacific oceans? Besides inducing an urge to go hiking, this post explains when you should capitalize oceans, mountains, lakes, and other geographic features such as rivers, deserts, and dunes.

Capitalize General Nouns in Proper Names of Geographic Features

Capitalize general nouns such as ocean, mountain, and lake, when writing proper names for individual geographic features:¹

The Indian Ocean is deeper than the Atlantic Ocean.

The Blue Ridge Mountains are part of the Appalachian Mountains.

Lake Michigan provides Chicago’s drinking water.

But, see Consult Your Style Guide Before Combining Proper Names of Geographic Features with a Plural General Noun below.

Lowercase Standalone General Nouns for Geographic Features

Lowercase standalone general nouns, such as dunes, lake, mountains, and desert, even if you have already used the capitalized proper names in the text (as shown in the first example below):²

Everyone should visit the Indiana Dunes. The dunes offer hiking, swimming, and picnicking.

The children wanted to go swimming in the lake, but the water was too cold.

The couple enjoyed camping in the mountains and off-roading in the desert.

Consult Your Style Guide Before Combining Proper Names of Geographic Features with a Plural General Noun

Consult your style guide before combining proper names of geographic features with one plural general noun (e.g., rivers, deserts) because our primary style guides offer conflicting guidelines for capitalizing that general noun.

For example, The Associated Press Stylebook recommends lowercasing the plural general noun:³

The Fox and Illinois rivers converge in Ottawa, Illinois.

Alternately, The Chicago Manual of Style recommends capitalizing the plural general noun:⁴

The botanist is studying vegetation between the Great Basin and Mojave Deserts.

Pro Tip: If your organization doesn’t follow a specific style guide, I strongly suggest following The Chicago Manual of Style for general business writing and The Associated Press Stylebook for journalistic writing. Check out “What Is a Style Guide?” and “Alternative Style Guides” for more options.

Now, where are my hiking boots?

Further Reading: How to Write the Names of Ships and Boats

References

1. The Associated Press Stylebook 2020–2022 (New York: Associated Press, 2020), 170, 200, 216; The Chicago Manual of Style, 17th ed. (Chicago: University of Chicago Press, 2017), 8.53.

2. The Associated Press Stylebook 2020–2022 (New York: Associated Press, 2020), 170, 200, 216; The Chicago Manual of Style, 17th ed. (Chicago: University of Chicago Press, 2017), 8.53.

3.The Associated Press Stylebook 2020–2022 (New York: Associated Press, 2020), 170, 200, 216, 261.

4. The Chicago Manual of Style, 17th ed. (Chicago: University of Chicago Press, 2017), 8.53.