Great Blue Hole
The Great Blue Hole is a giant marine sinkhole off the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll from the mainland and Belize City. The hole is circular in shape, across and deep. It was formed during several episodes of quaternary glaciation when sea levels were much lower. Analysis of stalactites found in the Great Blue Hole shows that formation took place 153,000; 66,000; 60,000; and 15,000 years ago. As the ocean began to rise again, the cave was flooded. The Great Blue Hole is a part of the larger Belize Barrier Reef Reserve System, a World Heritage Site of the United Nations Educational, Scientific and Cultural Organization (UNESCO).
Woods Hole (passage)
Woods Hole is a strait in Massachusetts separating the Elizabeth Islands from the village of Woods Hole on the mainland of Cape Cod. It is one of four straits allowing maritime passage between Buzzards Bay and Vineyard Sound. The others are Canapitsit Channel, Robinson's Hole and Quick's Hole. Woods Hole is often referred to as Woods Hole Passage to distinguish it from the village of Woods Hole, which is itself named after the passage.