Chris Kohl's "Dive Ontario Two!" (1994, page 132) describes a location for the City of Owen Sound/Saturn. The wreck is not mentioned in his other, more recent books that I know of.
There is a shoal on marine charts known as Saturn Rock that is just off the channel coming out of Stokes Bay on the north side of Lyal Island. Kohl attributes this rock's namesake as the City of Owen Sound/Saturn. He gives the following as "directions": "Line up the last two buoys at Stokes Bay and head out to 85 feet (25.5 metres) of water, and you will be at the site of the Saturn." That's it for directions-- no GPS coordinates, etc.
My parents used to have a cottage in the lee of Lyal Island, but I never did find the wreck or dive it. Mind you, I did not spend much time trying.
Kohl also references a 1901 article from the Duluth Evening Herald that describes the loss. It mentions the wreck as being abandoned 40 miles northwest of Southampton, and that the crew of 12 effected a landing in one of her small boats only seven miles from Southampton. The Lyal Island lighthouse was erected in 1885, and the site proposed by Kohl would be within sight of this light. That the crews spent 7.5 hours in the lifeboat, going 33 miles back towards Southampton while within sight of the Lyal Island lighthouse seems odd to me, although I suppose things would not always go to plan in such a storm.
I am leery of the site report, and am just reporting what I have in "Dive Ontario Two!" If you go searching, there is a boat ramp at Lakeside Park if you turn towards Lake Huron at Ferndale on the Bruce Peninsula and go straight to the lake. The ramp is right behind Lyal Island. If yo cant find the Saturn, there is another wreck called the Goudreau nearby (mostly broken up steel plates left after it was salvaged), and some other points of interest around Lyal Island including a cement hulled tugboat (high and dry on shore, as well as the remains of the old light station. A description of the sights was publishing in a kayaking newsletter at
Circumnavigation of Lyal Island