From oblivion to buried treasure: Seven weird/scary/awesome holes

Saturday, November 15, 2014, 1:00 PM - It seems our readers can't get enough of mysterious holes in the ground.

Case in point: One of the most popular stories on our website this morning are the shots from Siberia's unexplained sinkhole.

Here's a look back at our feature on seven holes, natural or man-made, that stand out because they are super fascinating, stunningly beautiful, or plain terrifying.

The Bayou Corne, Louisiana

Even the mere threat of sinkholes can be a nightmare for property owners: You can take every precaution to keep your home safe, secure and insured when suddenly the landscape outside your window starts eating itself.

Go to around the 15-second mark of this YouTube video:

That's the Bayou Corne sinkhole, and you just watched it silently suck those trees down into the depths of the Louisiana swamp.

It was first discovered in August 2012, prompting Louisiana to declare a state of emergency. Since then it's only grown, reaching nine hectares at last count, and it's forced the evacuation of around 350 nearby residents, many of whom planned to retire there (When the landscape isn't sinking into oblivion, it's actually a nice spot).

IMAGE: J.C. Winkler/Flickr

It seems to have been due to the partial collapse of a salt dome, an underground salt deposit, and the company that operates it has been fined $260,000 (it's facing lawsuits from residents, although several have accepted buyouts). 

Making matters worse: Toxic gas was detected near several of the area's homes, and while this source says the amounts aren't high enough to be a threat, the gas is one of the reasons officials say the evacuation could last several years.

The Guatemala City sinkhole

This sinkhole in Guatemala City, meanwhile, isn't in a rural area, it's smack-dab in the middle of one of Central America's largest cities:

It opened up in 2010, and when you look at the aerial pictures, it looks like a bad photoshop. But it's actually 30 metres deep and 20 metres across, so big that in the shot above, you can't even see the bottom.

These guys took a camcorder to the edge of the massive hole, displaying more courage (or foolishness) than we would:

A small factory plunged into the depths, along with a security guard whose body was never recovered. 

Very heavy rains of a metre or more from Tropical Storm Agatha are often cited as one of the causes of the collapse, but the tipping point was the poor sewage system beneath the area, which allowed water to seep through the loose volcanic pumice on which much of Guatemala City is built.

With that kind of foundation, the city is no stranger to sinkholes, and the 2010 hole is about the same size as one in 2007 that killed three people. 

Soon after the 2007 hole opened up, the government redirected sewer pipes in the area at a cost of $2.7 million, and filled the hole with a special kind of concrete at an unknown but probably hefty cost. Repairing the 2010 hole probably cost at least as much.

The Great Blue Hole, Belize

And off the coast of Guatemala’s neighbour Belize, we have this ominous, but beautiful submarine sinkhole:

Image: USGS

You’ve likely seen it before, and it’s one of countless underwater sinkholes found from Australia to the Red Sea to the Caribbean.

At 300 metres across, and 125 feet deep, it’s believed to have formed thousands of years ago, when sea levels are lower than they are now. A dive team led by the legendary mariner Jacques Cousteau found stalactites, which only form in the presence of dripping water, around 40 m down, although the chemical composition of the site is such that the waters at the hole’s deepest point are poor in oxygen and lifeless (it's the dark spot in this orbital shot).

Image: NASA

It’s popular with divers and recreational mariners, even though we just can’t shake the feeling of dread when we think about looking over the side and seeing a black, forboding abyss instead of the shallow turquoise of the rest of the reef.

Didn’t seem to bother these skydivers, though:

The Great Blue Hole is not the deepest underwater sinkhole, believe it or not. 

That crown goes to Dean’s Blue Hole, which is an astounding 200 m in depth. It’s a Mecca for freedivers looking to break the record for greatest depth reached without breathing apparatus (like the guy below).

One person who tried ended up dead. Goes to show how, in the natural world, beauty and danger can coexist quite comfortably.

The Sacred Cenote, Mexico

Back on shore, this sinkhole is a place of death not by an accident of nature, but by design:

Image: Salhedine/Wikimedia Commons

It’s known as the Sacred Cenote, steps away from the ruined Mayan city of Chichen Itza on the Yucatan Peninsula.

It’s just one of many naturally occurring sinkholes eroded into the limestone base that makes up much of the thickly-jungled region, and when it was unearthed more than a century ago, divers recovered not just bowls, cloth, carvings and artifacts, but also several bodies of children and adults bearing signs of human sacrifice.

Sounds awful, but to the ancient Mayans it was essential to appeasing the rain god Chaak. The Yucatan has no real rivers, and these sinkholes were an essential source of water in a region where drought could see the water table drop by 7 m or more. 

The Sacred Cenote is pretty murky as you can see, but others can be quite clear and are popular with cave divers:

The Mayan city-states were an advanced and populous civilization that needed a steady supply of water, so making sure the rain god was satisfied was something they took very, very seriously.

How seriously? Well, one of the Mayans’ many innovations was a special kind of dye known as Maya Blue, a resilient pigment that retained its sparkle even after centuries of burial or submersion.

The bottom of the Sacred Cenote is coated with a layer of that pigment that is four metres deep in some places. 

We have trouble believing that amount of dye residue could have come solely from the sacrifice of artifacts and people, but it’s clear the Mayan's were definitely a bit on the religious side.

NEXT PAGE: Is Captain Kidd's treasure buried in Nova Scotia?