Hole in one! Billionaire fishing tackle magnate discovers cave system under his golf course after a sinkhole opened up and he decided to investigate 

When a massive sinkhole swallowed tons of earth at his exquisite golf course in Missouri, experts told billionaire fishing tackle magnate Johnny Morris to fill it and get back to normal business. 

But instead of panicking, the cave enthusiast saw an opportunity to explore and set to work unlocking a natural mystery.

The 68-year-old founder of outdoors megastore Bass Pro Shops was intrigued by the possibility that an unknown cave system lay underneath the Top of the Rock Golf Course near Branson, in the Ozarks mountain range.

Scroll down for video 

A huge sinkhole opened up at billionaire fishing tackle magnate Johnny Morris's golf course in Missouri, so he decided to investigate

Hole in one: Morris found a fascinating network of caves underneath his course in the Ozarks mountain range

Excavation: The dig uncovered tall limestone formations that Morris believes are further clues of caverns 

Morris, who listed by Forbes as the 397th wealthiest person with an estimated net worth of $4.4billion, made his fortune in the tackle business after spending much of his free time in his college years fishing.

Eventually, he collected the best fishing tackle he could find from around the U.S. and sold it, along with homemade bait, from his father's liquor store.

Before he knew it, Morris created the Bass Pro Shop Catalog in 1974 and opened the first of his now 98 stores seven years later.

Over the years, he has developed a love for caves and discovered several himself, including one on property where the golf course now stands. 

On a cold day in 1993, he and fellow cave enthusiast Jack Herschend ventured inside a hole in the earth they found on the billionaire's expansive grounds.

'Man, I was so excited to be potentially the first person ever in that cave,' Morris said.

Morris opened Top of the Rock Golf Course in 2014. A year later, after days of heavy rain, a sinkhole 40ft deep and 70ft wide opened along the putting green 

Government experts suggested filling the hole in and going back about normal business, but Morris set about investigating what caused it to appear 

He dubbed it 'John L's Cave' - his middle initial is L - and a National Geographic photographer went inside and described it as 'an underground chapel'.

'It's a beautiful, pristine cave,' Morris said. 'Just magical in there.'

Morris opened Top of the Rock Golf Course in 2014. A year later, after days of heavy rain, a sinkhole 40ft deep and 70ft wide opened along the putting green. 

No one was hurt, but golf course officials 'were in a panic', Morris said.

Government experts suggested filling the hole in and going back about normal business. But soon, water from a pond drained into the hole, and a worker who happened to be near John L's Cave reported a torrent of water pouring through the cave.

'So I knew there was a connection,' Morris said. 'And that's when we started to dig.' 

 Every day, one backhoe at the bottom of what is now a 100ft deep hole painstakingly moves dirt to a ledge, where a second backhoe removes it one scoop at a time

'People say I'm crazy': Morris said the dig was worth the money - but would not reveal how much he has spent 

The dig uncovered tall limestone formations that Morris believes are further clues of caverns. 

Every day, one backhoe at the bottom of what is now a 100ft deep hole painstakingly moves dirt to a ledge, where a second backhoe removes it one scoop at a time.

The same circulating groundwater that causes caves to form can also cause sinkholes, said Doug Gouzie, a Missouri State University cave and sinkhole expert. 

The U.S. Geological Survey says states like Missouri, Florida and Texas that have large areas of underlying water-soluble rock are most prone to sinkholes. Missouri has nearly 16,000 sinkholes, including one encompassing 700 acres in mid-Missouri.

Gouzie said there is likely a cave system beneath the golf course, but what is not known is how spectacular - or ordinary - that cave might be.

Morris said: 'Whether it's just like a foxhole thing you have to crawl in or whether there's big caverns, that's the mystery, and that's the exciting part of all of this,' he said. 

'People say I'm crazy but I'm happy about every nickel we've spent down here,' he added, without revealing how much he had spent on the operation.