Man shocked to discover human remains beneath property that had been in his family for over 50 years

American YouTubers went down an unexplored sinkhole and found human remains.

ActionAdventureTwins created a YouTube channel based on their adrenaline-filled activities, mostly anxiety-inducing cave explorations in America's most dangerous caves.

Whilst their hobby might not be for everyone, their adventures are worth the watch!

In their latest video, they were joined by fellow explorer Davis (@CaveChronicles), to check out the sinkhole that had been untouched for decades.

They explored a massive sinkhole on private property after a homeowner mentioned its mysterious presence in his backyard. He had lived there for over 50 years but never knew what lay beneath.

"He said he threw a rope down it and it was 200 feet drop before it stopped," the narrator said in regards to the homeowner.

It didn’t take long before they stumbled upon something unexpected.

Just a few minutes into the cave and the YouTubers came across what looked to be human remains.

"Dude there's so many bones down there," one of them said.

Among the pile of remains, there was what appeared to be a human cranium and femur, arranged almost like a shrine.

"Dude, this is gonna blow that guy's mind who drove us here," one pointed out.

As they ventured deeper, they found evidence of previous explorers including an old rope dangling from above.

After testing the depth of the cave by tossing rocks, they estimated another drop of about 45 feet.

Trusting a 'rusty carabiner' left behind by someone else, the duo rappelled further into the dark abyss.

Atlantide Phototravel / Getty

The cave walls contained sparkles, which are bacteria that create golden reflections on cave ceilings, and flowstones coated the surfaces.

Deeper still, where they claimed they 'can't even see the top,' the explorers found rimstones and countless stalagmites, leaving viewers in awe.

It's a pretty claustrophobic watch if you're not a cave-diving fan but fascinating nonetheless.

Fans of the channel praised the siblings for their bravery, calling their content 'fascinating' and 'incredible.'

"Thank you. This is so cool and fun to watch," one user wrote.

"Love your adventures guys, thanks for the inside look into the planet. Safe travels," another viewer added.

"stunning , you guy are soo brave and your adventure is much appreciate it," someone else remarked.

One viewer confirmed the suspicions of human remains, writing: "My girlfriend and I are watching from Canada! We’re both paramedics, definitely a human femur and a human cranium. Thanks for making the awesome content!!"