Many experts have voiced their concerns related to the fact that we might know more about the Moon than about the Earth's oceans. Of course, by extrapolation, Earth is less familiar to us than it should be, and perhaps this has perpetuated lately neglectfulness as the source of so much trouble. Here are just a couple of facts that are definitely less common knowledge.

For starters, you should know that Everest is not the highest mountain on Earth. It is the highest one above the sea level, true, but calculating from its base to the apex, its height of 8,850 meters only makes it a second best. Actually, the world champion in this field is Mauna Kea, the famous volcano from Hawaii, which only rises 4,205 meters over the sea level, but there's much of it that doesn't show. According to calculations of the portion of the mountain that stretches beneath the ocean surface, its total height of 10,314 meters pretty much leaves Everest wanting.

The second interesting thing about our planet involves digging holes all the way through it, in order to reach from one continent to another, somewhat similar to Jules Verne's journey to the center of the Earth. Due to the complicated processes of gravity, if you dug a diametrical hole through the core and further on to the exact opposite side, and you fell in it (assuming you would be protected from the heat), you would accelerate until getting to the core, and then decelerate until reaching the surface again, on the other side.

Your average speed would reach 7.7 km/sec (5 miles/second) during the whole 42-minute trip. Then, you would fall back in, and repeat the process infinitely. Even stranger, if you dug any hole connecting any 2 points on Earth (even a shallow chord, not necessarily a diametrical line), the trip would have exactly the same duration. If you're interested, dig in for more.