Investigator Strait is a body of water in South Australia lying between the Yorke Peninsula, on the Australian mainland, and Kangaroo Island.

[3] Investigator Strait is bounded by Yorke Peninsula to its north and by Kangaroo Island to its south.

Flinders identified its boundaries with the following adjoining bodies of water - Gulf St Vincent and Backstairs Passage.

Flinders noted that Backstairs Passage is a body of water separate to Investigator Strait.

A number of protected areas are located both within and adjoining the Strait’s extent.