The largest cutters operated by the Coast Guard are the Polar-class icebreakers. Designed specifically for open-water icebreaking, these ships have reinforced hulls, special icebreaking bows and a system that allows rapid shifting of ballast to increase the effectiveness of their icebreaking. The cutters Polar Star (WAGB-10) and Polar Sea (WAGB-11) are among the world's most powerful non-nuclear icebreakers. Their primary missions include scientific support in the Arctic and Antarctic, and ice escort of shipping and logistics support for U.S. government interests in both polar regions.

In addition to providing support to scientific stations, the Polar-class icebreakers are equipped to serve as major scientific platforms. Laboratories, offices and dedicated quarters are provided for 20 scientists and technicians, giving them the capability to do at-sea research on geology, oceanography, sea-ice physics and other subjects in some of the most remote polar regions.

These ships are 399 feet overall, have a beam of 83.5 feet, draw 32 feet of water and displace 13,190 tons. They are designed to break ice up to 21 feet thick, and are crewed by 134 men and women. They carry 1,359,200 gallons of propulsion fuel, giving them a range of 28,275 nautical miles at their economical speed of 13 knots. They are propelled by triple shafts, turning 16-foot diameter, four-bladed, controllable pitch propellers. They have a combination diesel-electric and marine gas turbine plant; the diesel plant can produce 18,000 shaft horsepower and the gas turbine plant approximately 75,000 shaft horsepower. These ships also carry two ski-equipped Coast Guard H-65 Dolphin helicopters during major deployments, which are used to carry out scientific support, ice reconnaissance, cargo transfer, and search and rescue as required.

History of U.S. Icebreaking