A "gravity hole" sounds a lot like a black hole, but that's not what it is. It turns out that gravity is not the same all over the earth, meaning you could weigh more or less in different parts of the world. However, weight is just a number on a scale, and you wouldn't look any different. Water, on the other hand, is very much affected by gravity. There's a spot in the Indian Ocean where the gravity has much less force, and the water level is up to 106 meters (348 feet) lower than in the rest of the earth! See, water flows in the direction of gravity, and the area outside of this gravity hole has more, so the water flows away. That's a lot of water, since this area, officially known as the Indian Ocean Geoid Low (IOGL), covers an area of three million square kilometers (1.2 million square miles)!
The cause of variations in gravity is the composition and density of the earth, in this case the earth below the ocean. The IOGL was discovered in 1948, but it is only recently that scientists have discovered the reason for it. Its origin goes back 120 million years, when the tectonic plate carrying India crashed into Asia and raised the Himalayas. Read that story at Big Think. -via Atlas Obscura
(Image credit: ESA – GOCE High Level Processing Facility)