The far west of Tanzania features three of the most remote and least-visited national parks anywhere in Africa, namely Gombe Stream and Mahale Mountains, with their habituated chimpanzees, and a more conventional safari destination in the form of Katavi. Geographically, the west is dominated by Lake Tanganyika, which follows the Rift Valley floor for 675km (419 miles) -- the world's longest freshwater body -- to form the border with the Congo. Hemmed in by tall green hills, this beautiful lake is reputedly the least polluted in the world, with crystal-clear water to substantiate this claim and entice swimmers. At least 3 million years old, Tanganyika is also perhaps the world's most biologically rich aquatic habitat, supporting at least 500 fish species, of which the great majority occurs nowhere else. At night, this undeveloped lake is scattered with hundreds of lamp-lit fishing boats bobbing like a distant swarm of fireflies.

Kigoma, though not exactly a metropolis, is the largest port on the east shores of Lake Tanganyika. The gateway to Gombe Stream, the town is seldom visited by tourists now that there are direct charter flights to Mahale and Katavi, but it's a very pretty and amiable spot, set on green slopes enclosing a deep natural harbor. Kigoma is also an important public transport hub, serviced by daily flights and a railway from Dar es Salaam. It's also the main terminus for the venerable lake steamer MV Liemba, which was railed up from the coast in the dying years of German colonial rule, and still plies passengers and goods up and down the lake once a week.

Kigoma was chosen as regional administration center by the Germans, in favor of the older port of Ujiji, a 19th-century Arab slave trading center situated just 6km (3 3/4 miles) farther southeast. Unimposing as it is today, Ujiji is the site of arguably the most famous enquiry ever made on African soil: "Doctor Livingstone, I presume?" as posed by Henry Stanley to the mislaid Scottish explorer on November 10, 1871. The site where Stanley met Livingstone is marked by a shady mango tree and brass plaque, as well as the somewhat undercooked Livingstone Museum, whose centerpiece consists of life-size papier-mâché statues of the explorers' doffing their caps in greeting. Also worth a look is the traditional harbor, where local fishermen and boat builders ply their trades.

Only 52 sq. km (20 sq. miles) in extent, Gombe National Park -- also known as Gombe Stream -- is renowned for the groundbreaking chimpanzee behavioral research project initiated there by Jane Goodall in 1960. Despite its association with this renowned primatologist, Gombe is too inaccessible to attract significant numbers of tourists, but -- along with the more southerly Mahale -- it is undoubtedly the finest chimp-tracking destination in Africa. First habituated by Goodall, the 45-strong Kasekela community (the largest of the park's three chimp communities) is still remarkably approachable and relaxed with human visitors, making for a wildlife encounter as exciting and evocative as any in Africa. Locating the chimps can be quite strenuous, however, and it may involve hiking for an hour or three along steep, rocky slopes covered in thick miombo woodland and pockets of riparian forest. Accessible only by boat and explorable only on foot, Gombe supports good populations of olive baboons, often seen beachcombing on the lakeshore, as well as red-tailed, blue, and red colobus monkeys, and around 200 bird species.

Roughly 30 times larger than Gombe, and at least its equal as a chimpanzee-tracking destination, Mahale Mountains National Park is also wonderfully scenic, rising from the deserted sandy beaches of the 700m (2,296-ft.) lakeshore to the 2,441m (8,006-ft.) summit of Nkungwe in the Mahale Mountains. The park is home to around 1,000 chimpanzees, split among more than a dozen communities, one of which, comprising around 80 individuals, has been habituated and studied by primatologists from the University of Kyoto since 1965, and is also used for tourist visits. This community is no less habituated than its counterpart in Gombe, but it does occupy a larger territory, so it may take longer to locate them, especially during the wet months from November to April, when hiking is tougher. Chimps aside, Mahale supports varied fauna, including eight other primate species, including yellow baboon, red colobus, blue monkey, red-tailed monkey, vervet monkey, an endemic race of Angola colobus, and two types of galago. It is also home to forest creatures more typical of West Africa, such as brush-tailed porcupine and giant forest squirrel, alongside familiar East African species such as elephant, lion, buffalo, roan antelope, and giraffe. At least 230 bird species are present.

Inland of Lake Tanganyika and southeast of Mahale, the 4,530-sq.-km (1,767-sq.-mile) Katavi National Park is the most underpublicized of Tanzania's major savannah reserves, attracting fewer than 20 parties of tourists per calendar year for much of the 1990s. The park's profile is a little higher today, but not much -- and it remains ideally suited to safarigoers seeking a genuine wilderness experience. The main vegetation cover is dense miombo woodland, interspersed with a series of wide floodplains that flank the Katuma and Kapapa rivers and form lush marshes during the rain, but retreat almost completely during the dry season from June to November, when they attract immense herds of wildlife. Elephant, buffalo, zebra, giraffe, and various antelope are abundant, and lion and spotted hyena are also likely to be seen on a daily basis, while residual riverine pools attract mind-boggling aggregations of several hundred huddled hippo. Away from the floodplain, game is less plentiful, and the thicker vegetation is favored by the park's legendarily vicious tsetse flies. Katavi is best avoided in the rainy season from November to April, when game-viewing tracks often become impassable and the mosquitoes go mental.