Grand Lake is the largest lake in Newfoundland, covering approximately 543 square kilometres (about 132,000 acres) along the Humber River. It was formed when a paper milling company dammed the outlet of the original lake in 1925 to generate hydroelectric power, raising the water level over 100 feet and flooding the Humber Valley for over sixty miles. The resulting lake reaches depths of nearly 1,000 feet in places. The shoreline is rocky and rimmed with forest and towering cliffs, set against the eastern fringe of the Appalachian Mountains.

Grand Lake is considered big water and is recommended for advanced paddlers only. Weather can change within minutes, with winds capable of rising to dangerous levels very rapidly and temperatures dropping sharply. Paddlers have reported taking on water in open canoes during sudden squalls, with conditions deteriorating too quickly to don rain gear or PFDs. The lake should be treated with the same respect as open ocean paddling.

Grand Lake is typically paddled as part of a multi-day trip of 150 kilometres or more, often combined with Sandy Lake and Birchy Lake downstream. One common route runs from the junction of Highway 1 and Route 402 via a dirt road put-in, past Sandy Point, Glover Island, the Red Indian Brook confluence, and the small community of Howley, continuing through Sandy Lake, Seal Bay, and on to Birchy Lake. An alternative put-in is at the southwest end near Grand Lake Brook. Access to Deer Lake via the Humber Canal is also possible from the lake system.

The lake is nearly uninhabited, with the small town of Howley being the only community directly on its shores. Just outside Howley, the Grand Lake Tourist Camp offers camping facilities. A limited number of hunting and fishing lodges operate on the feeder lakes. All types of motorboats are permitted on the lake except personal watercraft, though launch facilities are limited. The many inflowing streams support trout and landlocked salmon, and wildlife is described as abundant, including sought-after game species. The lake is especially popular with kayakers and canoeists, and its shoreline is a draw for wildlife photographers.