BY Pittsburg Morning Sun

What was known as "The Circle" in the early 1900s has now become used for a completely different purpose.

"The Circle" was formed when a group of small mines were joined together by blasting and dropping out the ceiling of the mines, creating what was said to be the largest open pit lead and zinc mine in the world.

"This was called that because there were mines in a circle and all the pillars were blown and it was made into a circle mine," said John Mueller, president of Captain John's Sports and Scuba, which is located at "The Circle". "In the early 1940s, this was the largest open pit mine in the world."

Today, "The Circle" is used for a completely different purpose.

Divers from all over the Midwest will travel to the area just between Pittsburg and Webb City, Mo. to utilize the unique underwater terrain and depths reaching 230 feet.

Roads into "The Circle" create different floor levels in the lake and each level, according to Mueller, can accommodate divers of different skill levels.

"We have a lot of diving and lakes in the area but that is what we specialize in right here," Mueller said. "We have had people here from New Zealand come here for instruction."

Visibility usually ranges from 10-20 feet on the surface. At depth, below thermocline, it's always clearer and visibility reaches 30 or more feet.

Water temperature on the surface hits 70 degrees or more in the summer. Below thermocline (usually about 25-30 feet deep) the water remains 45-50 degrees all year.

Dive instruction happens in three stages.

Mueller said the first part is academic and includes book work and study. The second stage is confined diving in an on-site indoor pool, then instruction moves to the open water in the quarry.

"There are certain safety rules that you must know," Mueller said. "It is just like driving a car and there are things that you have to be aware of before you strap yourself in the car."

In addition to open water and freediving, "The Circle" also provides the ability for tec, or deep diving.

In fact, Mueller said that in 2003 a team of tec divers reached a train that was rumored to be abandoned in one of the mine shafts in the 1940s.

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