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  • Coming up next on Jonathan Bird's Blue World,

  • Jonathan dives a really deep and spooky blue hole in the Bahamas!

  • All of this today on Jonathan Bird's Blue World!

  • Hi, I'm Jonathan Bird, and welcome to my world!

  • ( ♪ music )

  • Everyone knows that the Bahamas have beautiful beaches and lush coral reefs. But they're

  • also world-renown for cave diving. And in the Bahamas, cave diving usually means blue

  • holes.

  • In particular, the island of Andros has dozens of blue holes, clearly visible from the air.

  • Walking through the forest here on Andros, you can see that the forest floor is the remains

  • of an ancient sea bed. This limestone was formed by coral reefs millions of years ago.

  • Rain, combining with carbon dioxide in the atmosphere creates mild carbonic acid---otherwise

  • known as acid rainwhich slowly dissolves limestone.

  • Millions of years of rain falling on this rock and then draining in, have slowly dissolved

  • away the rock, creating these odd little crevasses and holes. And it has made the whole floor

  • of the forest look like a gigantic piece of Swiss cheese.

  • Some of the holes have gotten pretty big. I mean this one is the size of a hot tub.

  • But in a few places, the holes are enormous, and full of water. These are the Blue Holes.

  • It's easy to see how the blue holes got their name. Andros is covered in them. They look

  • like circular ponds from the air, and often lead into vast underwater cave systems.

  • I have teamed up with Small Hope Bay Lodge and divemaster Mike Hornby to explore The

  • Guardian, one of the more famous Blue Holes on Andros. It's a hike through the brush

  • to get there.

  • MIKE: We have about a quarter of a mile we are going to have to carry our gear in.

  • JONATHAN: I gotta walk all the way in here in my full scuba gear?

  • MIKE: Yep!

  • JONATHAN: Oh man!

  • MIKE: Well, we don't have too far to go. We're just about ready to round the corner

  • and it's going to open up into a beautiful blue hole. OK, Jonathan, here it is. This

  • is the Guardian Blue Hole!

  • JONATHAN: Wow! It doesn't look that blue.

  • MIKE: If you look off in the distance there and you see that little bit of an archway,

  • that is going to lead into one cave system, and right down here, this is the entrance

  • to our other cave system.

  • JONATHAN: So this is where we're going down?

  • MIKE: Yes. So the Guardian blue hole is the portal for the cave systems that lie underneath.

  • So, I head back to get my camera.

  • This is a lot less convenient than boat diving.

  • It takes several trips to get my camera, plus all the other gear, to the water.

  • What I want to know is who was the first guy to discover this muddy hole and say "Hey,

  • this would be a good place to go for a dive!" I mean, look at it.

  • Back at the truck, Mike and I start suiting up. We will walk in our gear to the water.

  • Mike, as a cave diving instructor, will be my guide to exploring the blue hole. Mike

  • wears some specific gear for cave diving, including redundant dive computers, an extra

  • regulator and he will even be carrying a spare scuba tank.

  • So I'm not quite as technical as Mike, but I do have some specialized gear for cave diving.

  • I have a scuba tank, it's a normal scuba tank, but it has an H valve on it. It has

  • two separate independent first stages. So I've got my normal regulator that I always

  • use on the first one and a completely separate, redundant backup regulator on the other one.

  • So that way I can turn one off, turn the other one on, and if I have a problem with either

  • one of my regulators, I have a completely secondary backup. For lighting, my lights

  • on my camera, my huge video lights, those are my primary lights. But I have a flashlight

  • in my pocket and a chemical light stick which you break and it glows and you have 12 hours

  • of light. It has no batteries and that's probably more lights than I'm going to need.

  • With our gear all assembled and ready, we hike into the brush. And man is it hot! Nothing

  • like a long walk in the hot Bahamian sun wearing full scuba gear and a wetsuit to burn off

  • a few calories!

  • MIKE: This water is going to feel extremely good after that warm walk through here.

  • JONATHAN: Oh yeah, I'm looking forward to that!

  • Finally it's time to jump into the water and explore the Guardian.

  • JONATHAN: Oh that feels so good!

  • Well, it's time to go check it out!

  • As I sink down into the yellowish-green water, I can hardly see because it's so murky.

  • I'm following Mike's pink fins. He specifically uses the brightest pink he can find so the

  • people following behind can see him in limited visibility.

  • Cameraman Tim is right behind me, bringing up the rear as we sink down into a dark spooky

  • hole in the ground.

  • As we descend, we pass through layers of what looks like smoke in the water. Mike points

  • out these clouds of suspended sediments to me as we keep sinking.

  • The blue holes leads into a huge cave system and it's a lot deeper than you might imagine.

  • Periodically Mike turns to make sure we are still here, and his flashlight illuminates

  • a permanent guide line that previous divers have installed. This line guides the way out

  • in case we get disoriented.

  • The walls on each side of us go straight down. We are sinking into a deep crack.

  • As we get deeper, the walls get closer together, but the water gets clearer. We have passed

  • into seawater from the freshwater above. I can taste the salt on my lips. If we could

  • go far enough, eventually we could reach the ocean.

  • Mike points to ancient fossilized seashells imbedded into the limestone. Here's a conch

  • shell.

  • Our bubbles are hitting rock overhangs and knocking off sediment which is raining down

  • around us, reducing the visibility.

  • I continue to follow Mike, until finally at a hundred and fifty feet deep; we reach some

  • stalactites in a formation called candle wax. These were formed by dripping water during

  • the last ice age when sea levels were much lower and this part of the cave was dry.

  • Down below me, it's more than 500 feet deep in this cave. I don't think we'll be going

  • down there!

  • We turn around and start heading back, with Mike continuing to point out fossils.

  • Following our guideline back into the shallower, murky water, Tim is right behind me.

  • And Mike, with his spare scuba tank slung under his arm, is right ahead.

  • Periodically, markers on the line point the way out. These can be used in the event of

  • a light failure to feel your way to the surface.

  • At last we can see the dim glow of daylight from above as we ascend towards the sun.

  • Back in the shallows of the blue hole, Mike shows me around.

  • The bottom looks like its sand, but it's actually a deep layer of silt.

  • While Tim hovers high above the bottom to keep from kicking up the silt, I perform a

  • little experiment.

  • Down on the bottom, I plunge my arm into the silt up to my shoulder and it's even deeper

  • than that. This is a layer of decomposing leaves and other organic stuff. The decomposition

  • creates hydrogen sulfide, a deadly gas that smells like rotting eggs. The water is saturated

  • with hydrogen sulfide and I can smell it in the water that seeps around the edge of my

  • mask.

  • Wow. That dive can only be described as spooky. The water is kind of colored like mustard,

  • and you can't really see where you are going, and it's all swirly and if I wasn't following

  • Mike I would have been totally lost. That dive was very spooky but really interesting.

  • The next day I'm out on the ocean, suiting up for another dive. Mike has something he

  • wants me to see. After the last dive, I can't imagine what crazy thing he is thinking now!

  • I roll into the water and follow Mike and his trademark pink fins down to the reef.

  • Then we keep going down into a cavern below the reef.

  • At the bottom of the cavern, Mike points to a hole and motions for me to go in ahead of

  • him. Once again, it's pretty spooky, but exciting at the same time. So in I go, with

  • Tim and Mike right behind me.

  • Inside, it opens up into a big cave. We're not deep enough for stalactites though.

  • As we come around a corner, I look straight up to see light coming in from above through

  • a huge crack in the rock.

  • We make our way right up the fissure into the blue above.

  • I'm in an ocean blue hole, formed just like an inland blue hole 20,000 years ago during

  • an ice age, when the ocean levels were much lower. Once the ocean levels rose, this blue

  • hole ended up underwater.

  • But this blue hole connects through a vast labyrinth of caves to the inland blue holes.

  • And as we emerge into the open ocean, something looks weird.

  • When the tide goes out, all the water from inside the caves gets sucked out into the

  • ocean, bringing with it silt and hydrogen sulfide from the inland blue holes! It forms

  • clouds near the bottom, with a distinct line between the clear ocean water above, and the

  • silty hydrogen sulfide layer below. What you are seeing here are the decomposing remains

  • of forest vegetation which have passed entirely through the caves and out into the ocean!

  • Everywhere I find what look like strands of mucus floating in the water. It's most likely

  • mucus secreted by the coral in response to the caustic hydrogen sulfide.

  • It's stuck on everything, including this gorgonian, which has closed all its polyps

  • to protect itself from the hydrogen sulfide. As the tide carries the toxic water away,

  • the corals will go back to normal.

  • Finally, we head back to the boat. Tim and Mike hang on to the anchor line to do a short

  • safety stop before we surface.

  • My exploration of the Guardian blue hole on Andros was both fascinating and a little spooky.

  • But I have to admit I'm intrigued. There are quite a few more blue holes on Andros

  • for me to explore, so I'll be back!

  • ( ♪ music )

Coming up next on Jonathan Bird's Blue World,

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巴哈馬藍洞潛水|JONATHAN BIRD的藍色世界 (Blue Hole Diving In The Bahamas | JONATHAN BIRD'S BLUE WORLD)

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    Nemo Hong 發佈於 2021 年 01 月 14 日
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