Sounds typically have islands in them, however, the term is also used interchangeably with inlet, bay, and fjord.

So does Owen sound and parry sound have islands?

“Sound” when it relates to water comes from Germanic- and Proto Indo European languages. In Denmark, the Øresund (English translation “The Sound”) separates Denmark and Sweden. In Dutch, “zond” used to a be term for a sea-based water inlet into the lands. Many nordic languages still have “sund” in their vocabulary (Danish, Swedish, Icelandic, maybe Norwegian too?).

In Proto Indo European, the “swem” prefix is related to things of the water, or swimming. “Zwemmen” in Dutch still today means “to swim”.

Wiktionary gives the follow definition:

long narrow inlet, or a strait between the mainland and an island; also, a strait connecting two seas, or connecting a sea or lake with the ocean.

It also quotes a text from 1605:

The Sound of Denmarke, where ships pay toll.

Learned from information from New Zealand’s incorrectly named Doubtful and Milford Sound (which is also in the incorrectly spelled Fiordlands region), sounds and fjords are both valleys carved out of the land. The difference is what did the carving. Fjords were created by glaciers, whereas sounds were created by flowing water or other natural erosion processes. Sounds are often wider, less steep and can be more inland too.

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Also “strait”, not “straight”.