This is the longest lake in the world, and at 1,433 metres is the second deepest in the world (Lake Baikal in Russia is the deepest, at 1,738m). At its lowest point, Lake Tanganyika is 642 metres below sea level. It holds a volume of water seven times that of Lake Victoria, and while it is 677km long from north to south, its average width is only 50km. For divers and anglers, this is paradise, with over 350 species of fish, and some of the finest game fish in Africa, including goliath Tiger Fish and Nile Perch. You can even go body surfing after big storms, with waves reaching up to six metres, but buoyancy can be a problem in the fresh water. Right down at the bottom of the lake, the water is in places scientifically "dead" but is home to a rich history of fossil species and a thriving aquatic community. Avid snorkellers feasting their goggles on a dazzling array of tropical cichlid fish should keep an eye open for crocodiles.