The last morning of our trip found us in the middle of Gatun Lake. Formed by flooding the valley of the same name, it is the largest manmade lake. To create the lake, a board of U.S. Army and civilian engineers proposed damming the Chagres River near Gatun, where its valley narrows to a mile-and-a-half wide. To hold the 183 million cubic feet of water necessary to fill the lake, engineers designed the largest earthen dam ever conceived. Many Americans and international engineers doubted the feasibility of such a dam, but United States Army General and civil engineer George Goethals was confident. He authorized the creation of scale models to test the effects of water pressure on the various combinations of materials proposed for use in the dam. In this way, Goethals and his assistants designed and verified the integrity of the dam.

To build the dam, train cars dumped solid rock removed from the Culebra Cut onto two parallel ridges across the 1.5-mile-long site. The ridges, known as toes, were 4,000 feet apart and 60 feet high. Once the toes were in place, dredges pumped impervious clay from the surrounding river bottoms into the spaces between them. Ultimately, the stone and earth dam was a half-mile wide at its base, 500 feet wide at the lake’s waterline, and 115 feet tall. The dam contained 22 million cubic yards of material and covered 288 acres. In the center of the dam, engineers built a concrete spillway that could discharge 182,000 cubic feet of water per second if a major flood threatened the canal. On the other side of Culebra Cut and 32 miles away, a much smaller dam terminated the lake at Pedro Miguel. There the locks lowered ships into a 1.5-mile-long manmade lake that afforded navigation to the last set of locks at Miraflores. In total, all but 15 miles of the Panama Canal is traversed over lakes impounded by dams that were designed and constructed by the Army’s finest engineers.

We got to explore this amazing lake in various ways and in different locations. Whether guests chose a visit to the Rainforest Discovery Center or Barro Colorado Island (BCI) or a Zodiac cruise along the periphery of BCI, we all got the chance to see all the beauty this lake offers. Back on the ship to complete our canal transit, we crossed the last set of three chambers through the Gatun locks into the Caribbean Sea.