This Underwater Cave has a 300ft Tall Room! (Black Abyss)

Coming up, Jonathan and Todd dive deep into a very dark cave in search of a huge pit called the Black Abyss. Welcome to Jonathan Bird's Blue World! Todd and I have returned to one of our favorite cave diving destinations, Merritt's Mill Pond in Mariana, Florida. But we won't be diving here today. We head on over to Cave Adventurer's Dive Shop to meet up with our buddy Mehdi Zinedi. Hey Mehdi! How you doing man? I'm good Jon. Welcome back. Good to see you. Good to see you too. Do you remember Todd? Yes of course. Hey man. Welcome back guys. How are we doing? We are excited to go diving with you brother. Yes, me too. I'm going to take you to some special place today. Mehdi was one of our KISS Sidewinder instructors, and he promised to take us to a special cave when we returned. This is a wall system. The sinkhole itself gets pretty deep, so when we go down, we need to be careful. Today's destination is a spooky pit called the Black Abyss, located deep inside Leon Sink's cave system. Unfortunately, it's a 90 minute drive from the shop to the cave entrance. Five guys in a pickup truck with a bunch of scuba diving gear. Why can't we simply go wrong? Oh yeah! We're heading to Emerald Sink, located just south of Tallahassee, Florida. The Leon Sink's cave system is so huge that it stretches across two counties. As we pull up, we're not surprised to find we have the whole place to ourselves. Emerald Sink gets its name from its green, murky water, limiting its popularity. However, Mehdi knows all the local divers and keeps tabs on conditions. And we're pretty sure that we'll have the rare chance to see this cave with clear water. And he was right. It's so beautiful! Is it clear? Yeah! Oh, look how clear it is! Emerald Sink is a classic, picture-perfect sinkhole less than 50 feet across. But underwater, it opens into a massive chamber. With conditions looking perfect, the dive's a go. These are so much lighter than 85s. What did you do with this? Just stuff it in the flap? I rolled it up into a circle. Looks good. Since we're all wearing Kiss Sidewinder rebreathers, we're planning a pretty long dive. Mehdi and Patrick have placed some bailout gas near the exit, and ran a reel to the main line. So down we go. Emerald Sink is so huge that we can't even see the walls with the lighting from the sun. As we begin into the cave, the line is our only reference. Not long after we descend, we pass a tiny sink called Birdman's Sink. Actually, I don't really know if it has a name, but hey, Birdman's sounds pretty good don't you think? After that, we continue into the cave. It doesn't take long until we find a blind cave crayfish. They are everywhere in this cave. Living in the absence of light, these crustaceans have lost all their pigment and their eyesight. And this one seems to have lost a couple legs too. It might sound obvious to say that a cave is dark. But many Florida caves with their white limestone walls reflect our light's back. This cave has so much silt on everything that the walls are mostly black. The floor is black, the ceiling is black, and the cave feels very dark. Looking closely, I can see how the white limestone is just covered in silt. And much of the walls have been softened by the water chemistry, making the stone crumbly. On the floor of the cave, Patrick demonstrates the depth of the silt layer. Loss of buoyancy control in this environment would be catastrophic for visibility. And this is a perfect cave for rebreathers. Open circuit scuba bubbles would dislodge a lot of sediment from the ceiling. After about an hour, we finally arrive at the Black Abyss. It's a room too large to see across, and nearly 300 feet deep. Mehdi clips a light to the line at the entrance for scale. And then we take a lap around the circumference of the room. Mehdi tries desperately to light it up for our cameras, but we simply do not have enough lights with us. And we can't see the light on the line from the other side. Eventually we make it all the way back around to our light and start the trip back. I make another attempt at filming a blind cave crayfish, but unfortunately I spook him. This place is so silty, even a 2-inch crayfish can mess up the viz. On the way back, we take a slight detour through a side passage so we can visit another sinkhole. After a while, we arrive at Split Sink, named for its two entrances close together. Under every sinkhole is an accumulation of forest litter, and sometimes human litter, which we collect. As we get closer to daylight, we encounter non-cave species like catfish, and the skeletal remains of something. Finally, we swim all the way back to Emerald Sink and do our safety stop before surfacing. Our epic cave dive to the Black Abyss did not disappoint. We got lucky with uncommonly good visibility. But even then, we found the cave to be very dark and silty. The Black Abyss itself lived up to its name. The entire adventure took us almost three hours, but didn't seem that long because it was so much fun. Cave diving is always exciting, and every cave is a little different, providing a new adventure in the Blue World. Hey you guys! Check out that video! It's a really good one! Also this one is pretty good too! Oh, and don't forget to subscribe!