Ranger III is a 648-ton vessel built to carry visitors to Isle Royale National Park, on Lake Superior.

[5] As built, she was powered by a pair of two-stroke diesel engines, generating 614 shaft horsepower (458 kW), which were replaced by a pair of conventional diesel engines, generating 850 shaft horsepower (630 kW).

[2] While the vessel is capable of light ice-breaking, in late spring or early fall, the heavy ice of winter requires shutting service down.

[8] The Milwaukee Journal-Sentinel published a series of articles on the threats invasive species posed to vulnerable native species, which praised the National Park Service's initiative in equipping Ranger III with a state of the art system.

[10] On 29 July 2015, Isle Royale Queen IV ran aground, and Ranger III was called upon to bring the other vessel's passengers to the mainland.