Capitalization Rule: "Ocean" in "Atlantic Ocean" Is Lowercase

In the proper noun phrase **"Atlantic Ocean,"** only **"Atlantic"** is capitalized. The word **"ocean"** remains lowercase.

Rule

Proper nouns name specific entities. In geographic names with a generic term + specific identifier:

• Specific identifier (capitalized): Atlantic, Pacific, Indian, Arctic, Southern
• Generic term (lowercase): ocean, sea, river, mountain, lake, island

Examples

• Atlantic **ocean** — correct
• Pacific **ocean** — correct
• Mississippi **river** — correct
• Mount **everest** — incorrect (Mount is part of proper name: Mount Everest)
• Lake **superior** — incorrect (Lake Superior — both capitalized as compound proper noun)

Nuance: Compound vs. Phrase

Compound proper nouns (both capitalized): Lake Superior, Mount Everest, Cape Cod, Long Island

Proper noun + generic (generic lowercase): Atlantic ocean, Pacific ocean, Mississippi river, Sahara desert

Style Guide Variation

Some organizational style guides (e.g., US Navy, NOAA) capitalize "Ocean" in "Atlantic Ocean" as institutional convention. Standard English (Chicago, AP, Oxford) lowercases the generic. Consistency within a document matters most.