I've seen this many years in a row. Maybe you will have the chance to see a version of this nowadays. The first time we found it by the beach, carved on the driftwood forming the wall of this shack, was an invitation to chill. The more we looked and the more we marvelled at details: heart shaped out of a wire, small medal nailed to the wall, a small plastic bee by the entrance. It felt like we were in this fabulous tree house built by very resourceful (big) kids. The whole roofless structure seemed solid enough to withstand time. When I returned a couple of years later, it had been totally rebuilt into a more modest version, without most of the adornments. So it seems this is an ongoing project of rogue art. Look for it on the farthest half of the beach, where there usually is more driftwood. (Expect some mud around this fort after rainy days.)
During my last visit in June 2017, I didn't walk that far but saw some artists creating a giant maple leaf out of the driftwood. They were two artists from Drifted Creations (a company from British Columbia), commissioned by Toronto Parks & Recreation to create some art to lift the spirit of Torontonians, following the huge flood that impacted drastically any location by Lake Ontario. I don't know how long it will last but what a great initiative!