Icebreaker ships plow headlong into one of nature's most formidable barriers. Modern Marvels bundles up and goes for a sea tour aboard the toughest ships ever built, the massive icebreakers that can withstand hull pressures of 3,000 pounds per squar... (more)e inch. Experts like Gene Davis, the curator of the Coast Guard Museum NW, detail how these vessels have evolved from the age of sail, and how they have changed the way ships navigate in northern waters. Go on patrol with the USCG Cutter Mackinaw, one of the largest and oldest breakers working the vital North American fresh water shipping lanes, and then see the contrast as the USCG Healy, the newest Polar Class ice breaker in the American fleet, traverses the Northwest Passage on its maiden voyage. This is the story of the specialized ships that have turned the tables on one of the mariners' most ancient and implacable enemies.