The Panama Canal, cut through a narrow point in the mountainous isthmus that joins North and South America, extends for 50 miles from deep water in the Atlantic Ocean to deep water in the Pacific.
The original plans called for digging straight through the isthmus to build an uninterrupted canal at sea level. But rocky peaks looming as high as 312 feet above sea level along the Continental Divide forced engineers to opt instead for a system of locks to lift ships over part of the land mass and then lower them on the other side.
Three locks lift ships 85 feet and discharge them into Gatun Lake. (Photo Credit: ARED Networks)
It takes about eight to 10 hours for vessels to transit the canal -- about 24 hours counting the time spent waiting in line. Ships arriving on the Atlantic side enter the sea-level portion of the waterway near the port town of Cristobal and travel 6.5 miles through a mangrove swamp before reaching Gatun Locks. There a system of three locks lifts the vessels 85 feet and discharges them into Gatun Lake, which the builders created by damming the Chagres River. The lake covers much of the isthmus. Together with another, smaller dammed reservoir, Madden Lake, Gatun Lake provides the water needed to fill the locks. At the end of Gatun Lake ships pass through the Gaillard Cut, an 8.5-mile-long channel through the Continental Divide. Ships then pass through the Pedro Miguel Lock to Miraflores Lake, and then through the two Miraflores Locks, to return to sea level and emerge into the Pacific Ocean at the port of Balboa.
When the canal was completed in 1914 at a cost of some $375 million, it was hailed as a major feat of modern engineering. Not only was Gatun Lake the largest man-made lake at the time, but the dam was the largest earth dam ever built, and the locks were the most massive concrete structures ever assembled.
The canal has been improved and modernized over the years to accommodate heavier traffic and larger ships. In the 1930s, the Gaillard Cut, named for Col. David DuBose Gaillard, the engineer responsible for this section of the project, was widened to prevent frequent landslides from blocking the passage and to allow for two-way traffic. Other areas were widened in the 1950s and '60s to improve navigation. One of the most important improvements was the installation in 1963 of fluorescent lighting along the locks and the Gaillard Cut, which opened the waterway to round-the-clock use.
Since it opened, more than 825,000 vessels have passed through the canal. Today, most users travel between the U.S. East Coast and the Far East. Next in frequency are ships traveling between Europe and the West Coast of the United States and Canada. The canal is also a popular tourist route; about 300 of the 14,000 ships that use the canal each year are cruise ships.
Efforts began in 1992 to further widen the cut to improve safety and allow for more traffic. A further widening of the cut, to be completed in 2002, will allow unrestricted, two-way traffic of so-called “Panamax” vessels, the largest ships able to traverse the waterway. The Panama Canal Commission expects these improvements to increase canal traffic by 20 percent by 2005.
Further down the road, planners are considering building a second set of locks along the canal. “It's a hugely expensive project, and the technical feasibility will be determined by whether there is enough water to operate another set of locks,” says former Sen. Howard H. Baker Jr., R-Tenn., who helped gain Senate approval of the 1977 treaties that made the canal transfer possible. “But I do know that the canal is busy, and very efficiently operated, and I think it will continue to be an important waterway for a long, long time to come.”