Expedition

(pensive music) So down below us, and that line of vehicles there, is the rest of our team. (helicopter blades whirling) -

Narrator

Led by Hella, the ground team is transporting the three tons of specialist kit we'll need. We're driving up to that volcano, and the roads aren't exactly roads. (chuckles) We're all heading to a meeting point in the Harrat Khybar lava field, where geologists believe the longest lava tubes in Arabia could be found. (helicopter blades whirling) Wow. That's a biggie. There, that big one. So these are some of the volcanic craters, obviously extinct now, but super dramatic. And this is where a lot of these lava flows would have originated. There's another one over there. Amazing. During a volcanic eruption, the outside of a lava flow cools down and forms a crust. As the lava inside continues flowing, it leaves behind a void known as a lava tube. (dramatic music swells) The lava tubes here can be 40 meters in diameter, and hundreds of meters in length. We want to discover whether this underground labyrinth still holds signs of life from our ancient past. What we are looking for is a skylight, a hole that drops down into the lava tube beneath. And our aim is to get inside. Here we go, look, and see that, the hole? Wow. Wow. Yes, I see it. Yeah, there's definitely a line of them, isn't it? This is what we've been looking for. That bit there, yeah. Yeah, and then it runs off that direction, doesn't it? Several openings that line up. We'll mark that on the GPS. A sign there's a lava tube running beneath.