This is the Culebra Cut during construction of the Panama Canal. The United States Army Corps of Engineers was having a terrible time during construction because the ground where the canal was being built was unstable.  It had been a jungle for millions of years and there was no usable rock foundation. The Corps would dig down and when the trench got too deep, the sides would collapse into the diggings. So the Corps became off the wall thinkers. Instead of digging ‘down,’ they ‘dug up.’  They built up the outflow of the Chagres River where it entered the Caribbean and made a dam. That solved the problem.  Gatun Lake was completed in 1913 and, at that time, was the largest manmade lake in the world.  [See my books at https://authormasterminds.com/master-of-the-impossible-crime. See my webinar at http://bit.ly/2zjyiYG.]