The four-hour drive from the Toronto area to Tobermory is a trip known to many scuba divers from across Canada, and around the world. Tobermory lies at the northern tip of the Bruce Peninsula, an eighty kilometre strip of ancient dolomitic limestone forming the northern boundary of the geologic Michigan Basin.
A renowned destination for those wanting to explore shipwrecks dating from the nineteenth and early twentieth centuries, the waters around Tobermory also feature lesser-known yet equally spectacular underwater vistas for divers to journey much further back in time. During two recent dives in an isolated cove on the northern shore of the Peninsula just south of Tobermory, we explored a remarkable formation of dolomite rock bearing witness to glacial activity in the area 10-12,000 years ago, during the last ice age.

Words: Greg Hannigan     Photography: Jerzy Kowalczuk

In late November of last year, a month after the end of the ‘offi cial’ dive season, Jerzy Kowalczuk and I made the trip to Tobermory, eagerly anticipating an early winter dive when the frigid water temperatures of Georgian Bay ensure virtually unlimited visibility. Once there, we stopped at Diver’s Den to get a nitrox fi ll, in order to reduce our nitrogen exposure and prolong our bottom time, as compared to diving on air.

Fills completed, we drove the six kilometres to Little Cove and parked the Jeep about 60 metres from the water. After gearing up, we carefully navigated the softball-sized stones to water’s edge, enjoying the solitude of the wilderness setting as we contemplated the day’s dive. Pausing in knee-deep water to make fi nal gear adjustments, we pushed out and descended to a depth of about 2 metres. Making our way out from shore we swam across the shallow rock shelf, which extends about 100 metres north into Georgian Bay before it abruptly drops away to a depth of about 14 metres.

“We could easily envision the rock line as the furthest extent of a glacier’s progress as it scoured the bottom of the basin many thousands of years ago, pushing millions of tons of dolomite before it up against the Escarpment to form the shallow cove.”

Here, just outside the boundaries of the cove, the sand bottom is clean and devoid of rock. Looking back at about 7 metres’ depth we were awed by the panoramic view of a sharply demarcated boundary of large dolomite rocks and boulders, stretching almost infinitely into the distance on our right and left. With this perspective, we could easily envision the rock line as the furthest extent of a glacier’s progress as it scoured the bottom of the basin many thousands of years ago, pushing millions of tons of dolomite before it up against the Escarpment to form the shallow cove. After 90 inspiring minutes in this submerged Paleolithic paradise, we turned the dive and made our way back to shore.

There, over a thermos of hot tea, we agreed that we had to return soon to continue our exploration of this amazing site. In April we contacted another dive buddy to join us on a return trip, and the party of three set out for Tobermory once more. After four months of winter the water temperature, 2.8°C, was colder than November. However the spring sky was sunny, with ambient light flooding the cove’s shallows, highlighting colours in the rocks and providing a dramatic interplay of light and shadow for Jerzy’s camera.

We extended our exploration of the former glacier’s edge to the west, spending almost an hour swimming along the rock boundary at 12 metres, pristine sand to our right and a 6-7 metre wall of rocks rising immediately on our left. The return leg was spent at various depths between 6 and 1.5 metres, finning around, under and on top of the massive boulders, providing a good test of our buoyancy skills. Packing up our gear once back on shore, we determined to plan many more such dives into prehistory in the waters of Georgian Bay.

See more of Jerzy Kowalczuk’s work at underwaterpixels.com