An ice floe (/floʊ/) is a segment of floating ice defined as a flat piece at least 20 metres (66 ft) across at its widest point, and up to more than 10 kilometres (6.2 miles) across. Drift ice is a floating field of sea ice composed of several ice floes. They may cause ice jams on freshwater rivers, and in the open ocean may damage the hulls of ships.
Ice floes pose significant dangers due to their instability, unpredictability, and susceptibility to environmental forces. Unlike thick, grounded ice, floes are buoyant and mobile, drifting with ocean currents and winds at variable speeds. This movement can rapidly separate a floe from the shoreline or from other floes, trapping individuals or wildlife with no means of return. Structurally, ice floes are often riddled with hidden fractures and varying thickness, making them prone to sudden breakage or collapse under weight. Additionally, temperature fluctuations can weaken their integrity, while tidal shifts and wave action can cause tilting or rolling, creating crushing forces or ejecting occupants into frigid, hypothermia-inducing waters. For vessels, ice floes present navigational hazards as collisions with even modest floes can damage hulls or jam propellers, especially in poorly reinforced ships.
