How the Panama Canal Makes Water Flow Uphill

After seeing the relative success of Egypt’s Suez Canal, which opened in 1869, America envisioned a shortcut through Central America as a way of strengthening its position as a two-ocean power. That shortcut, known as the Panama Canal, cost $375 million (somewhere close to $11 billion today) and 10 years to build, with the project coming in at 444 percent over budget. More than 100 years after its opening, it remains an audacious example of American ingenuity and know-how—a true engineering wonder.

Early on, engineers debated the very nature of the Panama Canal. They finally abandoned ideas about a sea-level canal (like the Suez) when engineer John Frank Stevens instead insisted upon a different option—a locks canal.

A locks canal is comprised of a series of locks that raise or lower ships as needed. But in the building of the Panama Canal, that design necessitated construction of another big project: the Gatún Dam at the Chagres River.

Gatún Dam, at one time the largest dam in the world, had to be built across the Chagres River to ensure the proper flow of water between the Pacific and Atlantic oceans. That formed Gatún Lake, a major component of the canal’s seemingly uphill water flow. The water doesn’t actually flow uphill; rather, it is pumped into the canal chambers from the lake.

How the Gatún Locks Work

Completed in August 1914, the Panama Canal works as a “water bridge” in which ships are elevated at about 85 feet (26 meters) above sea level by a system of locks.

The Panama Canal’s locking system was chosen because the Pacific Ocean sits at a higher sea level than does the Atlantic Ocean. Rather than excavate down to sea level, engineers determined that the best option would be a series of massive locking gates that would raise ships above sea level into a large man-made body of water called Gatún Lake.

The locks are operated using the gravity flow of water from the Gatún, Alajuela, and Miraflores lakes. In order to allow ships to pass the lock, each chamber must be filled with 26.7 million US gallons of water. The same amount of water must be drained from the chamber in order to lower the ship again.

When a ship enters the canal from the Atlantic end, travelling in a southeast direction, the first entry will be into the first (sea level) lock chamber located at the Gatun Locks. After the ship enters the chamber, the watertight lock doors are closed by the lock-master and the valve is opened to allow the flow of water from the adjacent second lock chamber, 28 feet above sea level.

Water flows through underground pipes into the first chamber until the water levels are equal. However, no pumps are used there; the entire operation of equalizing the water levels between the locking chambers is dependent upon the principles of gravity to move the water and the fact that water seeks its own level.

When the water levels of two adjacent chambers are equal, the water stops flowing from the water culverts.

Once the water levels between the first and second chamber are the same, the valve gets closed by the lock-master and the watertight lock doors between the first and second lock chambers are subsequently opened.

This process allows the ship to proceed to the second lock chamber. The operation is then repeated between the second and third lock chambers, which raises the ship to the level of Gatún Lake.

To fill the chamber with water and raise the ship, the miter gates and lower lock valves are closed, while the upper valves are opened. The water from Gatún Lake rushes in through 20 holes in the chamber floor. It takes about eight minutes for the chamber to completely fill and raise the ship.

The ship then travels through the lake until it reaches the Pacific Ocean, where it enters the Pedro Miguel Locks, a single step that lowers the vessels 30 feet (9 meters) to Miraflores Lake, which is at an elevation of 52 feet (16 meters) above sea level. The ship then passes through a channel almost 2 km long to the Miraflores Locks, which consists of two consecutive steps, where the ship is lowered back to sea level on the Pacific Ocean side. The ship then passes through a final seven-mile (11.2 km) passage after which it enters the Pacific Ocean.

The entire trip—from the Atlantic Ocean to the Pacific—takes an average of 8 to 10 hours.