But just when we thought we'd seen them all -- alas! -- we stumbled across one type of waterfall we've never before considered: Upside Down Waterfalls.
These oxymorons are actually quite natural, albeit rare. Rather than defying gravity, as their name suggests, upside down waterfalls happen when strong gusts of wind blow against a waterfall's flow, thus forcing the stream of water to spray upward or blow backward.
So really, it's an optical illusion: upside down waterfalls only appear to be flowing in the opposite direction. Mother nature, you so silly.
Below, footage of upside down falls witnessed around the world, in all their windy glory:
Kinder Falls, United Kingdom
Kinder Falls, near Hayfield, normally cascades down 80 feet, but on a very windy day, the Kinder River can be stopped in its tracks and blow back upwards onto the Kinder Scout Plateau.
Cliffs of Moher, Ireland
The Cliffs of Moher, on the western coast of Ireland, are a site to see on any day, but imagine seeing an upside down waterfall there, too. According to travel blogger J.W. Ocker, it's important to go there on an especially windy day ("Like, blow Dorothy way past Oz windy") to experience the strong sprays.
Waipuhia Falls, Oahu, Hawaii
Waipuhia Falls turns into an upside down fall with powerful northeasterly trade winds, but it is very rare to see in real life. If it recently rained and the elements are just right, there are two ways to view them: driving down the Pali Highway eastbound (the falls will be on the right hand side), or an intermediate hike into the valley.
Rjúkandi Waterfall is located in the Eyjafjöll mountain range, one of Iceland's windiest regions. According to Iceland Magazine, the upside down fall is not an uncommon site.
As a bonus, here's an upside down fall with a rainbow because there can never be too much natural magic.
(This video is from an unknown location -- if you think you recognize it, please let us know in the comments below!)