Earth's Wildest Waters: The Big Fish

The six anglers travel to their most remote destination yet - the mighty Mekong River in Laos. Here people fish for survival, not for sport. The anglers must battle the blistering heat and the ferocious currents of the widest rapids in the world. They will use traditional bamboo rods, throw themselves into the local way of throwing cast nets, and use all their own experience and sport fishing equipment to see if they can discover anything in the Mekong that the local methods cannot. Matt Hayes will be joined by Mr Mai, the headman of his village on Baan Hangkon Island, to judge which angler leaves the expedition whilst the rest journey on. The heat, the terrain and the simple equipment make this the toughest leg of the expedition yet.

The five anglers head to Costa Rica to explore the Pacific Ocean and come face to face with some of the most incredible fish in the world. Fishing close to shore off the tip of the Osa Peninsula, the anglers seek out the fast and furious roosterfish and learn to lasso handlines like the locals in the rough surf, before heading offshore to seek the fastest fish in the world - the sailfish. The anglers have just one day to catch and tag this incredible fish, but things don't go quite according to plan. Matt Hayes adjudicates alongside local fishing expert Todd Staley, who has led the way in fish conservation in Costa Rica. Between them they must decide which angler to send home, whilst the rest make it through to the semi-final.

The four remaining anglers gear up for a semi-final of epic proportions, fishing for some of the biggest fish of their lives in British Columbia. Here, the whole ecosystem is driven by migrations of fish, so the anglers go on a journey of their own, fishing for Pacific salmon in the sea near Vancouver Island, fly-fishing for bull trout in the beautiful glacier-fed Upper Pitt River and taking on one of the legendary giants of the Fraser River - the white sturgeon. Matt Hayes will be joined by Yves Bisson, an expert Canadian fishing guide, to judge who goes through to the final.

The three finalists face their sixth country and their final frontier - Zambia. Navigating the immense Zambezi River, the anglers fish alongside wild animals on land and in the murky water. They search the croc-infested waters for huge vundu catfish, fish local style from wobbly dugout canoes and try to catch Africa's equivalent to the piranha - the tiger fish. They must use everything they have learnt across their worldwide expedition as the judges will be looking for which one of them is the complete angler. Matt Hayes is joined by Charles Tembo, who has grown up on the banks of the Zambezi, whilst Ben Fogle is with the anglers every step of the way on their final journey. The fish here have adapted to survive in these dangerous waters. The anglers have just one week to prove they have the courage - and the skills - to do the same.