What Is the Biggest Sinkhole in the World?

The largest sinkhole in the world is the Qattara Depression near Cairo, Egypt. The sinkhole, which is filled with sludge and quicksand, measures almost 50 miles (80 kilometers) long and 74 miles (120 kilometers) wide. The depression covers an area of about 7,000 square miles (18,130 square kilometers) — about the size of Lake Erie.