Douglas Channel is one of the principal inlets of the British Columbia Coast. Its official length from the head of Kitimat Arm, where the aluminum smelter town of Kitimat to Wright Sound, on the Inside Passage ferry route, is 90 km (56 mi). The actual length of the fjord's waterway includes waters between there and the open waters of the Hecate Strait outside the coastal archipelago, comprising another 60 km (37 mi) for 140 km (87 mi) in total.
A major side-inlet, the Gardner Canal, is 90 km (56 mi) in length, and is accessed from the Kitimat Arm of Douglas Channel via Devastation Sound (20 km, 12 mi), which is on the east side of Hawkesbury Island. South of Hawkesbury is Varney Passage (40 km, 25 mi), which has a sidechannel, Ursula Passage (30 km, 19 mi). Total waterway length of the fjord dominated by Douglas Channel is therefore, not counting smaller side-inlets, 320 km (200 mi), longer than Norway's Sognefjord (203 km, 126 mi) and rivalling Greenland's Scoresby Sund at 350 km (217 mi), though not as long as nearby Dean Channel's total of 335 km (208 mi).
Douglas Channel is a busy shipping artery because of the methanol import terminal (formerly methanol production and export) and the aluminum smelter at Kitimat, as bauxite must be shipped in and smelted aluminum shipped out. Recently announced (2005) plans will see a major expansion of the port of Kitimat as a container and bulk resources port, augmenting the port capacity of the British Columbia's North Coast currently a monopoly of the city of nearby Prince Rupert.