Question: Which canal or channel, the Houston Ship Channel or the Dismal Swamp Canal,  is part of the Intracoastal Waterway, which parallels the east coast and offers boaters shelter from the Atlantic Ocean from Manasquan Inlet, New Jersey, to Brownsville, Texas?
Sentence (from "Dismal Swamp Canal"): It is the oldest continually operating man-made canal in the United States, opened in 1805, and closed in October 2016.
Relevant evidence: No