As it leaves Ethiopia, Africa's Great Rift Valley splits. The eastern arm extends south from Lake Turkana through Kenya and Tanzania via the soda lakes, Masai Mara and Serengeti.
The western arm runs through Uganda via Lakes Albert and Edward, then through Rwanda's Lake Kivu before opening into the wide gash that is Lake Tanganyika in western Burundi. We arrived in a sweltering Nairobi just before the long rains.
A mere 50km west of Nairobi, the A104 drops into the Rift, an enormous valley with steep sides, its floor dotted with lakes, volcanoes and plains teeming with game.
Our truck halted for the night at Lake Nakuru. Although a small park, it didn't disappoint. The game densities were staggering. We threaded through endless herds of buffalo and common waterbuck; giraffes and gazelles were a dime a dozen, while black and white rhinos had regular walk-on parts.
The bird life was remarkable - flamingos, pelicans, storks, stilts and spoonbills. Hyenas, whose diet had become distinctly fowl, roamed the water's edge.
Climbing out of the Rift, we continued west, crossing the border at Malaba. After the dry and dusty browns of Kenya, the lushness of tropical Uganda was like a balm.
Every patch of land was cultivated and piles of green bananas lined the road. The towns were ugly, polluted and run down, but everywhere were markets bright with life, music, colour and mountains of fruit. We were heading for the Ruwenzori Mountains on the Western Rift Valley to see one of the world's largest remaining groups of wild chimpanzees.
From our camp on the edge of Kibale Forest National Park we could see the Mountains of the Moon, rising like a grey bulwark in the west. They're Africa's tallest range and mark the border between Uganda and the DRC.
At Queen Elizabeth National Park, herds of elephants ambled across plains or swam to islands in the lake. Ugandan kob (similar to impala) and buffalo dotted the land.
The south-western corner of Uganda is arguably its prettiest. In the distance were the volcanoes of Sabinyo and Muhavura; beneath them lay a land of cultivated valleys and lakes.
Ruhengeri, in north-western Rwanda, is in a horseshoe of volcanoes that are home to rare wild mountain gorillas.
