An ice pack or gel pack is a plastic sac of ice, refrigerant gel or liquid, or, in an emergency, even frozen vegetables. The refrigerant, usually non-toxic, can absorb a considerable amount of heat, since its enthalpy of fusion is high. It is commonly used as a cold compress to alleviate the pain of minor injuries or in coolers or insulated shipping containers to keep products cool during transport. The simplest type of ice pack is simply a sack, bag or towel filled with cubed or crushed ice.

Polar ice packs are large areas of pack ice formed from seawater in the Earth's polar regions, known as polar ice caps: the Arctic ice pack (or Arctic ice cap) of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean, fringing the Antarctic ice sheet. Polar packs significantly change their size during seasonal changes of the year. However, underlying this seasonal variation, there is an underlying trend of melting as part of a more general process of Arctic shrinkage.

Een ijszak is een plastic zak die ijsblokjes bevat om bijvoorbeeld een zwelling (hematoom) tegen te gaan.