Abstract: An apparatus for cooling refrigeration containers using pressurized liquid carbon dioxide is disclosed. The container has upper and lower compartments with a longitudinal distribution pipe located in the upper compartment which extends substantially the length of the container. The pressurized, liquid carbon dioxide is distributed through the distribution pipe in the upper compartment through a plurality of apertures located in the longitudinal distribution pipe which causes an accumulation of carbon dioxide snow in the upper compartment. The refrigerated gas cools the sidewalls of the lower compartment by passing through serpentine passages contained within those sidewalls. There are also switchable cooling vents which, when opened, allow refrigerated gas to pass from the upper compartment directly into the lower comparment.