Barrels (or tuns) were used for transporting all kinds of liquids, including water, wine, and spirits. They were essential at sea for 2 reasons: transporting food and drink, such as wine, oil, and salt to trade; and storing drinking water during the journey. In fact, as the only source of drinking water, they were indispensable.
They were usually handmade out of wood, cylindrical in shape, and bound together with metal hoops.