From Martin Frobisher in 1576 to John Franklin in 1845, generations of European explorers searched for a navigable route through the Arctic islands to Asia. Their greatest challenge was sea-ice, which has almost always filled the straits, even in summer. Climate change, however, is fundamentally altering the sea-ice conditions: In September 2007, the Northwest Passage was ice-free for the first time in recorded history. This Article reviews the consequences of this development, particularly in terms of the security and environmental risks that would result from international shipping along North America’s longest coast. It analyzes the differing positions of Canada and the United States with respect to the legal status of the waterway and argues that the end of the Cold War and the rise of global terrorism have changed the situation in such a way that the Canadian position—that the Northwest Passage constitutes Canadian internal waters subject to the full force of Canadian domestic law—actually coincides with U.S. interests today, as well as the interests of other responsible countries and shipping companies.