Cameron Lake drains into Cyprus Lake which drains into Horse Lake but where is the outlet from Horse Lake to Lake Huron? The answer is right here.
Originally Horse Lake drained overland into the lower elevation Marr Lake which is about 500 meters to the NE. The bedrock here is dolomite with numerous cracks and joints that allow water to collect. Over time the water dissolved and expanded these joints and underground passages formed. Water takes the path of least resistance and eventually the overland route was replaced by an underground plumbing system that connects Horse and Marr Lakes. This system of 5 sinkholes drains at capacity when water levels are high, reappearing as springs at the edge of Marr Lake. In late summer they are often dry as in the gallery image but at other times of the year you'll find water of varying depths in the sinkholes.
Such fissures, sinkholes and caves formed by the action of water on soluble rock are known as karst landforms and are very common features of the Niagara escarpment.
A National Park Display at the coordinates used to describe the sinkholes and other geological features of the area and pointed out that it takes 90 minutes for the water to travel from these sinkholes underground before it reappears in Marr Lake.however the display has deteriorated over the years and was finally removed in 2010. The sinkholes are located on the Georgian Bay trail and can be reached from the Head of Trails parking lot in Bruce Peninsula National Park (N45°14.178 W81°31.390)
To log this EathCache: visit the location and email me an estimate of the diameter and depth of the largest sinkhole and the depth of water in it at the time of your visit.
Continue on the trail to Georgian Bay and enjoy the spectacular scenery that this area offers.