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Frozen Ocean

Glaciers & Ice Sheets

Glaciers are large ice masses created by snowfall that has transformed into ice and compressed over the course of many years. An ice sheet is a mass of glacial land ice extending more than 20,000 square miles.

The U.S. Coast Guard icebreaker Healy moves through pancake ice in the Arctic's Chukchi Sea.

Sea Ice

Sea ice is frozen seawater floating on the surface of the ocean. Sea ice is formed entirely in the ocean, unlike icebergs, which originate from land-based sources like glaciers and ice sheets.