The Most Dangerous Cave in the World... (Mosdale Cave)

This might be the most dangerous video I've ever attempted. Wildly regarded as one of the most dangerous caves in the world, Mossdale is responsible for the worst recorded caving incident in history. In 1967, 10 young men prepared to venture down into the cave located in the Yorkshire Dales, England, as it was thought to potentially have kilometers of undiscovered unexplored passages. Mossdale was already known for being extremely dangerous because of unstable rocks, ceiling collapses, sections that were almost impossible to navigate in, but most importantly, flooding. The cave was extremely prone to flash floods. This is what the entrance looked like normally, and this is what it looks like under heavy rain. When this happens, any caver inside has a very limited time to escape. But with the group all being experienced cavers and the weather forecast looking good with clear sky, they decided to enter. After several hours, no one knows why, but four of the men decided to turn back around, while the remaining six continued deeper. Not long after the four returned to the surface, they made a horrifying discovery. The weather had suddenly started to turn as a thunderstorm started to rain down. The cave began to flood rapidly. They desperately tried to go back and warn the others, but already the entrance had filled with water. There was no way. All they could do was call for help. What followed was one of the largest cave rescue attempts the world has ever seen. Hundreds of people dug trenches, tried to divert the flood water, and worked around the clock to get the water level down while the six young men remained trapped inside. It took four days for the water levels to finally go down and be deemed safe to enter. A team of rescuers entered the cave hoping to find the men alive, hiding in one of the high ceiling caverns. But sadly, it was too late, as they discovered the lifeless bodies of all six men. It's believed that in under an hour, the whole cave had completely filled with water, and sadly, all six young men had drowned. Over the next few days, rescuers attempted to return the bodies of the men to the surface, but it was deemed too dangerous, so they were forced to leave them inside the cave, where they still remain to this day. Because of this tragedy, the cave was then permanently sealed with concrete and would remain that way for many years. That was until a few years ago, when after talks with the families of the victims, access to Mossdale was granted once again. Despite the cave being reopened, however, it's thought only a few people have been willing to go down inside because of the extreme danger it presents. And also many believing that the cave is haunted, with some claiming to have heard voices echoing in the tunnels. All of this making it too risky for even the most hardcore cavers. So when a caver who was one of only two people to have captured footage down there reached out to me wanting to take me down, I didn't exactly jump at the opportunity. But with extensive planning, preparation and a lot of consideration, me and my cameraman Sam finally decided to go down there. So is the entrance there? No, well it used to be. It used to be the entrance. Yeah, it's collapsed. So the new way in is around the corner. So there was an accident here a few decades ago. Some of the bodies were never recovered because it's so hard to get to the place they were. Yeah, and it just wasn't worth everybody else's lives trying to pull them out. Yeah, the fact that there's still bodies down there is a very scary... It is also a reminder of how dangerous this is. This is by far the most dangerous cave we've ever been to. Yeah, if it was a thunderstorm I'd be really worried. You really have to be very careful of this cave, especially this time of year in the summer because the weather tends to have more thunderstorms. There are some clouds and it rained a little bit earlier today but according to the weather forecast it's not supposed to rain. And this is the memorial of the people that passed away. And this cave was closed for decades, right? It was. I read somewhere that more people have been to outer space than down this cave. Do you think that's true? Probably, yeah. I mean, if you look online there's not much footage except for Maimon and Simon Becks. And I've only took a few people down here in my time. So yeah, it doesn't get frequented much. I mean, look, it's quite overgrown around here. You can tell people don't go in there very often. So this is the most scared I've been for a video, I think, ever. Having to rely completely on the weather forecast. If the weather forecast is wrong then this place is going to flood. We're trusting that weather forecast with our lives. Our aim for this trip was to reach Four Ways, one of the deepest sections of the cave that few people had ever explored. It would take around seven hours and it seemed like a logical place to aim for as it was where the potential for new passages begun. But already I was beginning to see how dangerous this cave was. This is the bit where I always get slightly confused. Way on. See, down there and down there. I think it's because the boulders moved at once. Yeah, that looks right, actually. The boulders moved? Yeah, a while back. I think this was the first time it's changed like that. This section of the cave was made up of tons of huge loose boulders. Dislodging one and being crushed was a real danger. This is why the entrance of the cave had changed so many times over the years. I had to be careful not only to not get stuck but also to make sure I didn't touch anything that could cause a collapse. Oh dude, this is so tight already. Definitely put your legs. Don't kick anything on that side. Okay. Keep coming down onto the floor. It's already more extreme than the... Yeah, it is. For sure. So how long would it take for this to... Like if it started pouring down now, how long would it take for the rain to like reach us or the... Probably an hour. Only an hour before this would be flooded? Yeah, because it's really dry outside. F***ing hell. Normally, I think we'd bring it off in three parts. Yeah. Having that in the back of your mind that like it could flood, that is what makes it so freaking terrifying. Like I'm not afraid of being stuck in a cave as long as it's dry. Yeah. But the wetness is just... That freaks me out. Head for it, yeah. Alex, have you ever caved with anyone where they just like completely panicked? I've had to drag somebody out who was crying once. I've seen your videos, Magnus, and you wouldn't want to do that. Yeah, I'm usually a very calm guy but we'll see later on when we get to the water. Oh, my leg is stuck in the... No, the backpack is stuck. Could you wiggle it out a bit, Sam? Thank you. After 30 minutes of extremely tight and delicate squeezes, we finally made it to the first place we could stand up. The boiler room. But even here, you couldn't feel safe. Right, so here, you'd be all right in most of the time but you can tell in the most extreme weather events, you're not because this is a bit of grass. So that tells you that the water's gone on all the way up to here enough to stick the bit of grass to the roof. So even in this big chamber, you're not safe in the worst of the floods. It's a scary thought being in here and then start filling up with water. That's like the worst way to die. It's like out of a nightmare or something. Yeah, I know. I feel sorry for the six people it did happen to. I can't imagine what that would have felt like. But what is worrying though is that this is the UK. I would trust the weather forecast a little bit more if it was somewhere else. Yeah, yeah, it's very fickle weather. That's why you have to keep checking it again and again. You see a couple of days ago, oh, it's fine. And then suddenly it's rain forecast. What I found interesting when we read the story about the people who passed away in this cave is that it was a group of, I think it was 10 or 12. But half of the group decided to turn around because they didn't feel something was off. And that like instinct, it's weird how maybe that is like something to listen to. Okay, so now it gets wet. Oh, God, dude. What the hell? This is already freaking snow, man. Seriously, are we going? This is drier than normal. Yeah. Insane, man. Alex had explained to us that the six men who passed in the cave all those years ago were buried in a certain secret chamber known as the sanctuary deep within the cave. We all agreed to avoid that part for obvious reasons. However, even after all these years, traces of their presence can still be found. I learned the marathon series a few years ago when I went to Stream End Cave. I found what's left of an olden light, and there's only one place that could have come from. Okay. It was just hung on the wall. It was quite spooky, really. So that's from the people that died then? Yeah, I can't think where else that would have come from. It's downstream of where they died, so it would have been washed out at some point. It's like the atmosphere in here, just like knowing that something so tragic happened in this cave also makes it so much more serious. You mentioned earlier that there's grading also in caving, right? Yeah, it's a simple system. It goes from one to five, one being the very easiest, five being the hardest. Right, and what is this cave? This is grade five. At the very end of the cave where we're going, well, not the very end, but near the end of the cave, it's called False Four Ways. And how many people do you reckon have been there? 50 have gone in the cave, I'd estimate, and probably 20 there, if that. I guess you could argue that out of the 20 who's been there, six of them died, right? Yeah, they would have been there, yeah. So the death rate technically is pretty high in this cave. I guess if you're looking at it racially, yeah, I never thought of it that way. Right, that's basically like 30% of the people who've been there have passed. Oh my god, dude. What the hell? No way. Oh my god, dude, no f***ing way. Just stick out and move slowly. Oh my f***ing god. Oh my freaking god. If it starts raining, we're not going to be able to get back from here. No, this is the choke point. Is there an alternative exit if we... No, we'll just have to wait it out. Jesus Christ. It's where it gets deepest, probably to your neck. But the water's been that bad. I've actually had to hold my breath for a very short distance. But it is going to get worse after that again. Eventually, yeah. When we get to the end of New Record, that's where it gets the wettest bit. While it was sketchy being this far into Mossdale, I could start to see how intriguing it was. The fact that so much of this cave had unexplored potential, and that we were entering passages that potentially no one had ever explored. As intimidating as Mossdale was, not knowing what secrets this cave could hold kept pulling me deeper. Oh wow, that's nice. So this is where if it started raining, we would wait it out. Yeah. But you say that if it rains a lot, then even this place will be flooded completely. Yeah, we're still below the entrance, so eventually the cave fills up. Yeah. And therefore the water eventually gets back to here and completely fills it up. Yeah. This place is enigmatic. There's a lot more to find in this cave. I just don't know where to look for this. The resurgence is many kilometers away. We also, at the climbing shop when we got this gear, they said there's a rumor that there's a guy down here who's like digging out new tunnels. Yeah. Some guy, weird guy. It's not you, right? No, no, I wouldn't call him weird to his face. Yeah, okay. Yeah, unfortunately he's not done it for a bit. He was down here 80 odd times now. And yeah, he's been dragging scaffolding bars through here to shore up his dig. He does it all on his own. He doesn't want any help. He just wants to do it all on his own. Do you think if I left you might just find your way back up? No, never. Or actually I'd like to think I would, but I know from just other caves that it's so much harder than you think. I think that I kind of remember where we went, but I probably didn't. Have I lost Sam? No, I think it's you. Right, okay. Sam? There's several ways you can turn back there. Sam? Lay up. Yeah, yeah. Excellent. Here's more grass up to the roof. So this is completely flooded. Now I really started to feel scared. Being this far underground was extremely dangerous. And the infamous knee-wrecker crawl lies just ahead, known as the worst part of Mossdale. Over half a kilometer long, it was an extremely tight passage that once you enter there was no way of turning around, with the ending having the tightest underwater squeeze in the whole cave. Oh, this is narrow. So if it starts raining outside right now, we're dead, basically. In this bit, yeah. As you can see, it's very low. I mean... And it's only a matter of one hour of pouring rain and this is going to flood. That is insane to me that you're willing to take that risk. Yeah, I mean, so are you. You're here with me. Yeah, yeah, that's a very good point. What is that rumbling sound? Just me. Is it just you? Yeah. ****, he's terrified. I felt like I heard like a deep bass rumble sound. I guess that's like the last thing you hear in a cave like this. Yeah, I'm trying not to think about that. This passage seemed to go on forever. We had been crawling now for half an hour and still weren't even halfway. This was by far the most claustrophobic and scared I'd ever felt in a cave. Dragging your body through hundreds of meters of rough rock and water was exhausting. And in this type passage with nowhere to turn around, rainfall now would mean almost certain death. And I still had the hardest bit to come. How are you doing? I'm doing good, but my knees hurt a lot. And this is sort of scary to be in such a long narrow tunnel like this. You feel so trapped. You can tell me to turn around if you want. That's always up to you. Turn around? If you want. There's a bit about halfway, about halfway down it. How are you doing, Sam? Good. OK? Yeah, I know. This is the worst thing I've ever done. It's like every part of my body just hurts. I know, me too. Amazingly, I found this moth which is alive. I just had to fly through my helmet. It's amazing that you can get in this well. Yeah. Seems almost like a bad omen. Yeah. Why? That moths like to do the devil or something, right? Now get off my hand, otherwise you'll drown. Get off my hand. I could feel the fatigue now as the crawl seemed never-ending and went on and on. But just as I thought this was the hardest caving I'd ever done, things were about to get even worse. Oh, dude, man. This is... Now I'm actually regretting this a bit. Like, honestly. Alex? Oh my god, dude. This is, I mean, this is the goal. This is, we've made it. It's hard, like, when you watch a video like this, you can't, it's hard to, like, describe how far this is, really. Like, we're very deep now, a few kilometers in. But yeah, no, I think we should try to rush out before, not spend too much time here in case it starts raining. I agree. Even though the original plan was to explore a little further, we decided we had had enough and wanted to get out. And although Alex reassured me everything was okay as we made our way back, to me it felt like the sound of the water was getting louder and louder and the water levels were rising. I wasn't sure if it was real or just a cave playing tricks on me. Not wanting to find out, we started to move as quickly as possible. Oh, I can see light. Thank you, Thor, for no thunder. Oh my gosh, that's the most claustrophobic cave I've ever been in.