A thermal bag is a special type of bag designed to maintain the temperature of food and beverages. The inner layer of a thermal bag is often made of insulating materials that help minimize heat exchange with the surrounding environment. Thermal bags can be used for both hot and cold foods and beverages. Thermal bags are ideal for picnics, trips or transporting food that requires specific temperatures. They are available in a variety of sizes and designs, often with additional pockets and straps for easy carrying.