Hastings Arm is a fjord on the North Coast of British Columbia, which is the northwest arm of Observatory Inlet, one of the two main branchings of Portland Inlet, the other being the better-known Portland Canal, which forms part of the Canada–United States border. Hastings Arm is approximately 30 km (19 mi) in length from the divergence of Observatory Inlet near the former smelting town of Anyox, where a 25 km (16 mi) east arm, Alice Arm, branches off towards its head at the mouth of the Kitsault River. This divergence is approximately 50 km (31 mi) from the mouth of Observatory Inlet itself, near , which is the outer part of the estuary of the Nass River. At the head of Hastings Arm is the mouth of the , and the Nisga'a village-site of .