Blue Hole (Castalia)
The Blue Hole captured the public’s interest because of its size, about in diameter, clarity, vibrant blue hue, and enigmatic "bottomless" appearance. Contrary to prevalent belief, the depth of the Blue Hole is not unknown, but has been sounded and found to be about deep. Water temperature is about throughout the year. Floods and droughts have no effect on temperature or water level. The Blue Hole is fed by a passing underground stream which discharges of water daily into Sandusky Bay to the north, feeding into Lake Erie. The water contains lime, soda, magnesia and iron, and because the Blue Hole is anoxic, it cannot naturally sustain fish. The surrounding terrain is developed on limestone bedrock and exhibits karst topography due to dissolution of the limestone by ground water, creating water-filled sinkholes. The Blue Hole was known to American Indians and was first recorded in history in 1761. Several similar blue holes are known to local residents. The Blue Hole that once was a tourist attraction is now off limits to the public. It is located on the grounds of Castalia Trout Club. It is to be distinguished from another hole similar in size and eerie bluish-green color. This latter hole is owned by the Castalia State Fish Hatchery operated by the Ohio Department of Natural Resources, Division of Wildlife and is open for public viewing.
O'Hare station
O'Hare is the 'L' station at the northwestern terminus of the CTA's Blue Line. It is a subway station with two island platforms serving three tracks, located at O'Hare International Airport, 17 miles (27 km) northwest of the Chicago Loop. The station is located underneath the O'Hare parking garage. Trains are scheduled to depart from O'Hare roughly every 2–7 minutes during rush-hour periods and take about 40 minutes to travel to the Loop. It is the westernmost station of the 'L' system. It is also the only station without coordinates in Chicago's grid system, as O'Hare lines up with no street in the city. It is the only underground terminus, the only terminal where a premium fare applies, and is the only terminal that does not directly connect to any CTA or Pace buses. It is also one of two terminals (the other being Dempster-Skokie on the Yellow Line) that does not have a yard assigned to it (the yard is located at Rosemont, one stop east).