A Geographic Fact Many Find Surprising
One of my odd niche interests is that I am fascinated by the Panama Canal and its construction. I probably have read 10 books on the topic. My kids know never to ask anything remotely about it because they will get a 1-hour lecture.
So here is your fun fact that all but other canal aficionados will find surprising: The Atlantic entrance to the Panama Canal is west of the Pacific entrance. The canal actually runs largely north-south rather than east-west as we imagine.
The other thing most people have wrong in their minds when they think about the canal is that they picture ships traveling through a narrow excavation. Pictures of boats are almost always at the locks or at the Culebra Cut. But for most of the route the sort of median view is of a ship sailing across a peaceful lake in the middle of a rain forest. The canal was made by damming two rivers and creating two lakes (one of them enormous) that spread out to cover most of the isthmus. The digging was then to connect the two lakes through the spine of the country (the Culebra cut) and to build flights of locks at each end up and down from the lakes. Thinking of the canal as a bridge over the land rather than a cut is a more accurate picture. This design solved the twin problems of too much digging (we'd still probably be digging in the Culebra Cut if people had insisted on make the canal at sea level, a vision that was surprisingly hard to get past) and the Chagres River which could become an incredible torrent in the rainy season and flood out everything in its path.