A Panamax vessel is a ship that has the maximum dimensions which will allow it to pass through the lock chambers of the Panama canal. Such a vessel has a maximum beam of 32.3 meters and lengths of up to 290 meters. The largest Panamax container vessels carry up to 4,442 TEUs with approximately 60,000 deadweight tons (dwt).
A plan to expand the Panama Canal's capacity was approved in 2006. This plan will improve the capacity of the lock system by adding a third set of locks. The new locks, dubbed Panamax II, will be 55 meters wide and 427 meters long. This lock set will handle vessels of 12000 TEU in size.