The 100km/70mi-wide delta forms a labyrinth of channels and lakes which converge at Beaufort Sea. It is the estuary of the huge, fast-moving Mackenzie River and the terminus of its 1,800km/1,100mi journey from the Great Slave Lake inland. It is one of the most abundant areas for wildlife in Canada's Arctic. The local economy, formerly based on trapping, hunting and fishing, has been transformed since the discovery of huge reserves of oil and gas under the Beaufort Sea.