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).
Blue Line (CTA)
The Blue Line, also known as the O'Hare-Congress Line and the West-Northwest Line, is a Chicago "L" line which extends through the Loop from O'Hare International Airport at the far northwest end of the city, through downtown via the Milwaukee-Dearborn Subway and across the West Side to its southwest end at Forest Park, with a total of 33 stations. It is the CTA's second busiest rail line, with an average of 186,796 passengers boarding each weekday in September 2012.