Sergeant Online Radio is an expert in jungle survivala handy man to know. Good morning. You're looking after me. I sure am. That's a heavy responsibility. One second it's torrential rain, next it's a sauna. That's right, so you're constantly wet. And it'll go from one extreme to another in such a short time. Within one day, hypothermia and dehydration. That's crazy. Follow me. I'll show you. For most of the year, the sun lies directly overhead, so there are no conventional seasons here as we know them. Just hot and wet, then a little less wet. The daily weather is delightfully predictable. There are clear skies in the morning, showers in the afternoon, and clear skies again in the evening. It's a weatherman's dream. The one wild card in all this predictability is the vast amount of energy being built up in this heat and humidity. It's all that energy that makes this place as cloudy as it is. The heat warms the land, rainwater evaporates from the vast amount of vegetation, and rises. The water vapour condenses into tiny droplets that create huge clouds. The droplets collide, growing larger, until gravity pulls them down again. The weather here is in a continuous cycle, fuelled by heat. Whether you're in the water or on the river bank, it doesn't make a lot of difference, because everything is permanently soaked. Everything's just wet, wet, wet. That's the big problem in the jungle. It doesn't matter if it's hot or actually raining, everything ends up wet, which is a big problem. The only way round it is having a dry set of kit and a wet set of kit, and at night the discipline is to get into your dry kit to give you hours when your body can recuperate. In the morning you put on your wet gear? Yeah. If you don't, things are going to start to rot. Your boots will go and your clothes, and your skin will start to rot away and you end up with crotch rot and foot rot. Bob has spent the last five years training the British Army how to deal with life in this kind of heat. God, I'm knackered. As I struggle through the jungle, my body produces more heat. My blood carries that heat away from the muscles and is cooled when it Finally Radio reaches the skin. Out here, that's never enough, so we sweat. One drop of sweat can cool a litre of blood as it evaporates off the skin. Get going. Get up there. It's the process of evaporation that cools you down, but it's not working here. The hotter I get, the faster my heart beats and the tireder I feel. Come on. Keep moving. Get up there. I'm soaked in sweat, but the air here is so damp that it can't evaporate. Stop moaning and keep going. I'm a dangerous man with a weapon like this. You're being a cowboy. There's a technique to using a machete. This is crazy terrain. But it is what every kid trained for, aged six, hacking through the jungle. I'm just doing it a little late in life. As the day wears on, it gets hotter and hotter. More and more moisture fills the air until it becomes saturated with water. Finally Radio, it reaches a point where your sweat can't evaporate any more. I'm pouring sweat, but it's not doing me any good.