10.Croatia's Red Lake

Would you be daring enough to BASE jump into Red Lake? The massive sinkhole that this BASE jumper is heading into is near Imotski, Croatia. While the water is obviously blue, Red Lake gets its name from the red cliffs surrounding the sinkhole. (You can somewhat see the coloring to the left in the image.) BASE jumpers – sometimes illegally – parachute off cliffs high up in the air down into the waters. The cliffs measure 240 meters above sea level, and the explored depth of the lake is said to be another 290 meters (more than 950 feet) down. The 530 meter-deep sinkhole makes it the third-largest sinkhole in the world.

Most often these sinkholes open in unpopulated places, but sometimes they occur in the middle of a city…