McNeil River, Brook in Kenai Peninsula, US.

McNeil River is a brook in Alaska's Kenai Peninsula that originates from glacial sources in the Aleutian Range and flows toward Cook Inlet. The river's natural geography creates waterfalls where fish congregate during their seasonal movement upstream.

The site was discovered in the 1940s, and after Cecil E. Rhode counted 32 bears in one day in 1954, the Territory of Alaska closed the entire drainage to brown bear hunting in 1955. The State Legislature designated the McNeil River a wildlife sanctuary in 1967, and in 1993 the protected area was enlarged to preserve the highest concentration of brown bears in the world.

The river is named after Charlie McNeil, a farmer from the region. Since 1973 the state has capped summer visitors at ten per day in June, July and August, and access is now allocated by lottery for four-day stays. The McNeil Camp has eight ranger cabins, eating areas and a tent camp.

Access is highly restricted through a state-managed lottery that limits daily visitors to 10 people during the main season from June to August. Visitors should prepare for remote wilderness conditions and variable weather typical of coastal Alaska.

The river's falls act as a natural barrier that concentrates salmon during upstream migration, creating one of North America's densest bear gatherings. When fishing peaks, as many as 74 brown bears can congregate in this area simultaneously.