High Quality Content by WIKIPEDIA articles! "Panamax ships" are the largest ships that can pass through Panama Canal. The size is limited by the dimensions of the lock chambers and the depth of the water in the canal. An increasing number of ships are built to the Panamax limit to carry the maximum amount of cargo through the canal. The increasing prevalence of vessels of the maximum size is a problem for the canal as a Panamax ship is a tight fit that requires precise control of the vessel in the locks, possibly resulting in longer lock time, and requiring that these ships transit in daylight.