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.
Paul Hosie
Hosie was born on 30 June 1967. He gained his Cave Diving qualification in 1997. Over the past ten years, Hosie has been involved in the discovery and mapping of over 10,000m of new cave passages in Australia. This has included the exploration of remote cave diving sites in Australia including Kija Blue Sinkhole in Australia's Kimberley region (ADM Issue 24/2006 ). Hosie has been recognised as a member of the World Exploration Team of Divers in Advanced Diver Magazine and was the recipient of the 2003 Oztek Diver of the Year Award.  In 2007, Hosie was awarded the National Speleological Society (USA) Cave Diving Section - Exploration Award along with his team members for the exploration of Kija Blue Sinkhole  Hosie has been active in the caving community in WA. He is currently exploring the area of Eneabba to find new caves and pay homage to Jeff Butt, who was the inspiration for the inaugural Australian Speleological Federation Award for Exploration that he was awarded in 2007 from the Australian Speleological Federation.