My Watermark is Lake Muskoka, Ontario.
My parents have a cottage on Lake Muskoka outside of Gravenhurst. My favourite memories over the last few years are everyone sitting on the dock, enjoying the sunshine and swimming out to the inflatable island that we have a few meters out.
We have two golden retrievers who love tennis balls and swimming in the lake (in that order). They are quite friendly dogs, but get annoyed if you don't throw their tennis balls with 3 seconds of them getting out of the water and will bark quite a bit. The older dog (Sophie) can manage one tennis ball, while the younger one (Molly), can take care of two. Seeing a dog jump into the water to retrieve a tennis ball is one of the most happiest things you can possibly see.