Translation guide
Refers to the Seto Inland Sea (瀬戸内海), the body of water separating Honshu, Shikoku, and Kyushu. In English, 'Inland Sea' almost always refers to this specific Japanese sea, so the direct translation is the proper noun.
the Inland Sea (in Japan)
Almost always refers to the Seto Inland Sea.
Referring to the specific sea in Japan
The standard Japanese name for the Seto Inland Sea. Use this in all contexts when referring to this body of water.
The Seto Inland Sea is known for its calm waters.
There are many islands in the Seto Inland Sea.
Referring to any inland sea, not specifically the Seto Inland Sea
The generic term for an inland sea. Use this when talking about inland seas in general, not the specific Japanese one.
The Mediterranean Sea is a type of inland sea.
A more technical term for inland sea, often used in geography. Less common in everyday speech.
In English, 'Inland Sea' capitalized usually means the Seto Inland Sea. In Japanese, 瀬戸内海 is always the proper noun. Use 内海 for the generic term.
The Caspian Sea is the world's largest inland sea.