NO OTHER sound is as humbling as the low, deep-throated roar of a lion as it reverberates beneath vast, moon-lit African skies, across dusty, acacia-dotted plains and on through the worn, dark green canvas of a safari tent. At first it sounds like a distant, unbaffled truck engine, fading in and out with the wind, but then it seems too close, too sinuous to be man-made. It is too throaty to be the thundering of a buffalo herd, or the charge of an elephant; too elastic in its slow, rolling cycle to involve metal. Elimination rather than recognition finally tells you it must be a lion. ''Simba,'' a Masai guard confirmed in reverent Swahili tones the following morning. ''Did you hear him last night?'' We had camped at Aruba Lodge in the 20,000-square-kilometre Tsavo National Park - the largest of Kenya's 31 national parks and game reserves - on our way from Mombasa on the Kenyan coast to Nairobi, the purple-tinged jacaranda city. Earlier we paid our 450 Kenyan schillings (about HK$100) entrance fee, headed into the park in our hired four-wheel-drive Suzuki and instantly began to experience the real Africa. Giraffe catwalked amid the trees elegantly - like hip-swinging Paris tarts; ostrich motored across our path, the black and white males outshining their mousy-coloured mates, and warthog, their half-manes flowing in the wind, thrust their tails in the airlike car aerials and trotted off, tusks at the ready, looking for all the world like extras from a Mad Max set. There had been plenty to see around the camp, too. Aruba overlooks a lake which in this vast dustbowl of a continent acts as a powerful magnet for game. You quickly learn that in Africa, water equals life. As the sun set we watched a herd of elephant trundle over the horizon, a squall of dust around their feet, eager to reach the water's edge where they drank, washed and played like a contented family. Maribou stork, looking for all the world like stooped undertakers on the lake shore, sat and clattered their beaks as the sun fell over distant hills. The light dimmed, and the noise which is Africa filled the air. Camping in Tsavo is as close as you can get to experiencing what it must have been like on safari in times past, when great white hunters set off on foot from Nairobi with hundreds of porters carrying tents, chairs, salt and silver tableware in order to partake of the particularly un-'90s sport of hunting. Some were not as adventurous, as David Garrick Longworth pointed out in The Globetrotter, an American travel journal of the '30s: ''In British East Africa, you may either elect to shoot big game from the second floor of your hotel, or to plunge pluckily into the jungle and engage the wild beasts on a catch-as-catch can basis.'' Either way, it meant death for thousands of animals. It was not unusual, for instance, for hunters to shoot six lions in one day. One game control officer from the period recorded the death of 996 rhinoceros on a single page of his diary. Some things at least have changed for the better. We left Aruba Lodge the following morning and drove south through the park and then across the Mombasa-Nairobi railway, built by the British at the turn of the century, which now serves to divide Tsavo into two parts. At one stage our path was blocked by a vast herd of buffalo - unpredictable beasts each weighing as much as a small car - and were forced to wait while they migrated across the track, snorting beneath their twisted horns. Finally, we reached the park's exit gate from where we could head west to the next stop on our African itinerary, the plains of Amboseli - or so we thought. When we arrived, cheery game rangers told us the road was dangerous, infested with bandits. A convoy would leave the following morning, they said, and we were welcome to join it. Alternatively, there was a man whose parents lived close to where we were going and who was willing to escort us. We accepted the offer. Eventually a boy no older than 16 sloped up wearing plain clothes and carrying a Kalashnikov in a canvas bag, with a small bundle of what looked like onions wrapped in newspaper. They turned out to be his grenades. He was a talkative fellow who told us his name was Chai and that he belonged to the Somali tribe, whose land lies northeast of Nairobi. He had three wives who lived in his homeland and whom he had not seen for many months. He asked to sit in the front ofour jeep with the window open, ''for better shooting''. Our journey took us through Masai country, where earnest young explorers had trekked 100 years ago in search of a source to this or that river. Caught by Masai warriors, they had been subjected to terrifying atrocities. The landscape changed from the familiar brown and grey bush to walls of black, lumpy tarmac-like stone which lined the route, some deposits considered very young by geologists. Standing on this lunar-type landscape it was possible to see across the Tanzanian border to the monstrous mass which is Mount Kilimanjaro, the largest mountain in Africa at 5,898 metres (19,340 feet). Ernest Hemingway immortalised it in his Snows of Kilimanjaro, while it is alleged Queen Victoria gave it away, unseen, to her cousin. The landscape became flatter once more, back to the familiar sun-scorched African colours - with one difference. Every now and then a pin-prick of red caught the eye. These were the Masai, swathed in tartan-like cloth, decorated by a million colourful beads and carrying spears and rungus - throwing clubs made from rock-hard wood and weighted with metal knobs. They sat on hillsides watching over their herds, always on the lookout for cattle raiders from other tribes who would sometimes attack, kill several cows, then chop off their heads and legs, remove the bowels and wear the carcass like some grotesque overcoat. This way, decked out like a headless pantomime horse, they could make good their escape. One lone warrior, his head covered with a hood of red cloth against the wind and dust, crossed a plain escorting a single, hit cow, a stray which he had retrieved from the other side of the valley. I reached for my camera. ''No pictures,'' said a soldier, ''or he will stone the car.'' We finished our journey in silence, aware Africa was, and always will be, a harsh place for man and animal alike. How to get there British Airways flies from Hongkong to Bombay, then transfer to Kenya Airways from Bombay to Nairobi. Cost: $8,100 for the whole trip (maximum stay 30 days). Visa: required.