The transit started before dawn

Ships are raised from the Caribbean, up to the Gatun Lake, in three steps, then down to the Pacific in another three making six steps in total. Each step has two channels, making twelve locks in total.

The first is the “Gatun”, with a flight of three steps.

The image above shows the “Brave Star” with one of the diesel powered engines called “mules” attached by ropes to the ship’s aft. There is another mule on the other side just out of the picture. The mules run on tracks and through skillful control keep the ship central in the channel. There are normally two mules each side at the front of the ship and one each side at the rear. The ships move forward under their own power, with the mules just preventing them hitting the sides.

The mules have to climb steep slopes to keep up with the ships as they quickly gain altitude.

Above is one of the original channels excavated by French engineers when they tried to dig the canal down to sea level, to avoid having locks. They failed after thousands of workers had died due to accidents, malaria and yellow fever. The project was eventually completed by American engineers by using the present system of locks and lakes.