The Panama Canal opened for business 100 years ago this month. By 2005, 5% of the world's seagoing traffic crossed it, including 70% of the cargo heading in and out of the United States. It remains, even today, a technological and logistical marvel.
This time-lapse video from ZipCams illustrates that by showing a day of traffic (April Fool's Day, 2012) through the Miraflores Locks. You can watch live camera footage of those locks here.
-via Gizmodo
Somehow they had to know that before they started digging their trench, otherwise, once they broke through to the water, the ocean on one side would have immediately poured into it and overflowed the ocean on the other side.