Yes, that passage happens to be in the sea, in the water. It's not at all the same dynamic as the freshwater we've been talking about, though.
That said, there's the whole issue of Canadian sovereignty over the Northwest Passage, an issue I would like to explore at this time. The United States agrees with Canada that it doesn't agree on this sovereignty, so it's not a defence priority.
Let me explain. Since the signing of the Arctic co‑operation agreement between Canada and the United States in 1988, our two countries have agreed to disagree. In other words, Washington respects Canada's position but says it disagrees every time Canada asserts its sovereignty. For its part, Canada respects the American position. So there's a kind of agreement that there's disagreement, without seeking to resolve the issue or force the other party to take another position.