What limits the size of ships in panama canal?

The Panama Canal has specific limits on the size of ships that can pass through its locks. These limits are known as the Panamax dimensions and are as follows:

- Maximum length: 965 feet (294 meters)

- Maximum width: 106 feet (32 meters)

- Maximum draft: 39.5 feet (12 meters)

- Maximum height above waterline: 190 feet (58 meters)

Any ship that exceeds these dimensions is considered "post-Panamax" and cannot fit through the canal. These ships must either go around South America, which adds significant distance and time to their journey, or be unloaded and reloaded onto smaller ships that can fit through the canal.

The Panamax dimensions were established when the canal was originally built in the early 20th century and have been unchanged since then. However, there have been discussions about expanding the canal to allow for larger ships, but no concrete plans have been made as of yet.