This is Willmotts General Store located in the Beaumaris area of Muskoka. Beaumaris is located on Tondern Island which you simply drive over a bridge to get to.
From Wikipedia: In 1873 McCarthy sold the island to Edward Prowse and John Harry Willmott for $1,560. The two divided the island in half with Willmott taking the northern and Prowse the southern half. The new owners named the settlement Beaumaris after the resort in Anglesey, Wales where they had vacationed. Prowse settled in the big white house while Willmott built a log house next to the site of the present day Willmott store. They cleared part of the land for pasture, built a dock for the newly arrived steamships and connected the island to the mainland by a small log bridge.