Highway 688 is a highway in the Canadian province of Saskatchewan. It runs from Township Road 472, Alberta across the Alberta-Saskatchewan border traveling west. The highway turns from westerly to northerly at Lone Rock intersects Highway 16. Highway 688 continues to a northern terminus at Highway 303 is about 21.2 miles (34.1 km) long. There is a second Highway 688 according to both Google Maps and Microsoft Streets and Tips which extends in a northerly direction 4.5 miles (7.2 km) south of Marshall, the northern terminus at Highway 16, the Yellowhead Trans-Canada.