An ice pack or gel pack is a portable plastic sac filled with water, or refrigerant gel. For use the contents are frozen in a freezer. Both ice and other non-toxic refrigerants can absorb a considerable amount of heat before they warm above 0 °C, due to the high high latent heat of fusion of water. These packs are commonly used to keep food cool in portable coolers or in insulated shipping containers to keep products cool during transport.

Ice packs are used in coolers to keep perishable foods (especially meats, dairy products, eggs, etc.) below the 5–75 °C (41–167 °F) danger zone then outside a refrigerator or freezer, and to keep drinks pleasantly cool. The amount of ice needed varies with the amount of food, its initial temperature, the thermal insulation of the cooler, and the ambient temperature and exposure to direct sunlight.