This first leg takes him from the rugged coast of South Africa, where he joins the fight against wildlife poachers, through Mozambique, and on to the tropical island of Zanzibar. On the way, he swims with sharks, meets the refugees who have found shelter in a luxury beachfront hotel, and travels on a huge container ship fortified against the constant threat of pirates.
The third leg of the adventurer's journey takes him from the south of Kenya to the Horn of Africa. Along the way he joins a Ugandan peace-keeping force in Mogadishu, the capital of war-torn Somalia, which turns out to be the most dangerous leg of his journey as he ends up under fire on the front line. In contrast, he finds neighbouring Somaliland a stable and democratic home to thousands of Somalis fleeing fighting and famine. In Kenya's Tana Delta, he meets villagers facing eviction from an area that the government is turning over to sugar cane production for bio-fuels.
The fourth leg of the broadcaster's journey takes him from Oman to the Maldives. He starts in the Strait of Hormuz, where oil from the Gulf is shipped through the narrow channel, then moves on to Mumbai, the ocean's biggest port. In the Maldives, Simon finds arguably the most beautiful collection of tropical coral islands in the world - but the fragile underwater environment is a barometer for the changing nature of the sea, as he witnesses how bleaching has damaged the coral and one entire island has been manufactured as a landfill dump to deal with the problem of rubbish.
The adventurer reaches Sri Lanka, whose strategic location and tropical spices made it a target for invaders and colonisers for centuries. In the north he visits the scenes of vicious battles between the Tamil minority and the Sri Lankan army, traumatic events from which the population is still recovering. On his way to Bangladesh, he hitches a ride on a trawler, highlighting one of the Indian Ocean's fastest-growing industries - providing prawns for the West. But as he reveals, it comes at a price for the environment.
The adventurer begins his final leg on the northern tip of Sumatra, near the epicentre of the 2004 Boxing Day tsunami, finding out how the province of Banda Aceh has undergone many changes since the disaster. He also explores the illegal trade in exotic pets in the Indonesian capital of Jakarta, before heading for Australia, the final country on his epic journey. There he visits the unspoilt wilderness of the Kimberley region, meets a real-life crocodile hunter and goes fishing with Aborigines campaigning to stop the construction of a giant gas plant.