The historical name for this rocky lake access - you can't really call it a beach - but in that vein you could call it a "rock" - was Elder's Dump.
I used come here with my high school sweetheart. We used to swim here with her kid brother. Also most of the local kids living around Little Pike Bay - called Shaw Road/Spry Road/Little Pike Bay Road now - would use this rocky swimming hole regularly, not to mention tourists and cottagers.
Elder's Dump is located at the end of Spry Road which runs from highway 6 west through Spry and butts into Lake Huron. The road just ends into an open area with plenty of parking. It overlooks an island about 1 km out, bunch of rock outcroppings, beautiful rock wall and there is a small pretty little beach a short hike north, but I do not know if it passes through private property.
The History so far!
Elders Dump. It seems it was one of the places that loggers would dump their logs and float them to the sawmill, but were not sure where that was. The history is a little sketchy at this point, but I will update as I research the topic.