Icebreakers: The Frozen Inland Seas explores icebreaking and rescue operations of several icebreakers as they patrol the frozen inland seas of the Great Lakes. During the harsh northern winters, the men and women of the United States Coast Guard smash through ice using nine icebreakers. The mighty Mackinaw is the largest and most powerful icebreaker on the Great Lakes. Her exploits are legendary. Breaking ice as thick as ten feet, she keeps the shipping lanes open and liberates freighters hauling valuable cargo trapped in the Great Lakes’ icy grip. Her service extends the shipping season on the Great Lakes, which is vital to the American and world economy. Join the crews of the icebreakers and freighters as the drama and danger of the annual “Spring Breakout” unfolds. It’s a ride you’ll never forget!