A cooler is composed of a number of stackable units. Each unit has inner and outer shells with an air space between them. The outer shell has bottom, side and end panels connected together forming an outer tub with a drain. An inner shell has bottom, side and end panels connected together forming an inner tub. Drain openings in the inner tub allow water to flow to the drain in the outer tub. The bottom panel of the inner shell is spaced from the bottom panel of the outer shell creating an air space therebetween. The bottom of one unit can nest in the top of another unit to stack the units one atop the other. Wheels are attached to the bottommost unit.