The document describes several large holes around the world, including:
1) The Kimberley Big Hole in South Africa, which is the largest hand-dug mine at over 1,000 meters deep and yielded over 3 tons of diamonds.
2) The Glory Hole at Monticello Dam in the US, which drains 14,400 cubic feet of water per second from the reservoir.
3) The Bingham Canyon Mine in Utah, which is the largest human-made excavation at 3/4 mile deep and 2.5 miles wide.
4) The Great Blue Hole off the coast of Belize, which is a stunning circular underwater sinkhole that reaches 145 meters deep.