But looking around, I found it hard to believe. The landscape was pure savannah - flat, dry scrubland - in all directions; surely we would have spotted an elephant already if there were that many? We supped and talked and for a moment I forgot we were in Africa. Then Lance, one of our guides, nudged me. Behind us, walking silently in single file around our camp to the water-hole, were about 30 elephants.
It was a scene straight out of a wildlife documentary. Tiny baby elephants, their trunks bent up imploringly, were running to keep up with their mothers. Huge bull elephants were striding protectively at the front and back of the procession. They passed our tents and went straight to the largest of the three adjoining pans - a natural water-hole surrounded by trees. Our dinner around the campfire was accompanied by their loud bellows ringing out as they splashed, played, argued and drank.
We were there specifically at the time of the full moon so that we could watch the game as they came to the water-holes both during the night and during the day. And although the sight of elephants striding past became a familiar one, I never really got used to it.
Over the next few days, I learned much about these impressive animals. They are a keystone species - many other animals, such as baboons, guinea fowl and impala, rely on them to spread seeds for them to eat - so without elephants, the survival of other animals and the vegetation would be jeopardised.
But there was more to this idyllic scene than first met the eye. There's trouble in paradise. There are too many elephants in Botswana.
This is because many are staying in Botswana because of war or poaching in neighbouring countries. Bizarrely, the saying that "an elephant never forgets" seems to be true - if one of the herd has been shot at in a certain place, they know not to go back, even months later. As our guide Dilys explained to us: "These aren't just Botswana's elephants, they're Africa's elephants - they come from Angola, Zambia, Namibia and Zimbabwe - so although there are too many elephants for Botswana to cope with right now, there aren't too many elephants for Southern Africa."
Botswana is also an extremely dry country and suffering the effects of climate change. The fact that the Botswanan currency, called "pula", means "rain" in the Setswana language, says a lot about the importance of water to the region. The twin problems of over-population and lack of water means elephants are congregating around the few water-holes that are left, and the result is a barren, decimated bush, with trees often eaten down to the ground. Many people have called for the elephants to be culled to protect the National Park. Others feel that such a drastic measure is unnecessary.
Our tour operator, Discovery Initiatives, links up with conservation and community groups in every country they operate in, and in this case, we teamed up with the Chobe Wildlife Trust's conservationist Ross Dwyer, and specialist local guides Dilys and Lance Spear of Safari Thanda Manzi. Our safari was consequently far from ordinary - at Tchinga pan we learned about how the bush works, what threatens it and how people are trying to save what they love so much.
Ross explained that we were to be involved in a project that Chobe Wildlife Trust hopes will prevent culling: old, dried out water-holes are being brought back to life with the help of solar-powered generators which pump water into an artificial pan next to the natural pan. During the day, the water then siphons through to another artificial pan and finally, to the original natural pan.
Our role was to monitor the number of game coming to the water-holes. Our 24-hour count would provide vital information for those deciding which water-holes to resuscitate. For a day and a night we crept around the camp, talking at a whisper and taking it in turns to sit in our camouflaged jeep a few hundred yards away from the water-hole and count the animals that came. At night, by the light of the full moon and with the help of binoculars, we watched intently - often finding that so many elephants came at once it was almost impossible to keep track of their numbers.
During our 24 hours we counted an incredible 406 visits by elephants, plus several visits by impala, zebra, monkeys, buffalo, giraffe and a jackal. After dark, we took it in turns to keep watch, lying on the top of the jeep, wrapped in blankets to ward off the night chill. It was wonderfully restful just lying there, stretched out in the moonlight, waiting.
My night watch was from 4am to the end of the 24-hour count at 8am. Elephants had visited regularly a couple of hours either side of midnight, and zebra and giraffe had also ventured in, but one look at the game-count sheet told me that, from about three o'clock onwards, the visits had diminished dramatically - only mad baboons and English people, it seemed, are out at water-holes at that time.
At 7.40am, after a fairly uneventful watch - a solitary roan antelope - a rare, endangered animal - appeared. She was startlingly beautiful. Her deep rust coat shone in the early morning light, her ears were pricked forward, attentive to every small sound, and eventually, four minutes before our 24 hours ended, she stretched her neck down to the water-hole and drank.
Dilys crept over to watch the roan with me. "Do you realise how privileged you are to see this?" she whispered. I did. It was an extraordinary start to another peaceful day.
Sue Wheat flew courtesy of Air Zimbabwe and travelled with Discovery Initiatives (tel: 0171-229 9881) which runs 13-day safaris in Botswana, including Chobe National Park, and is involved in 48-hour elephant counts from May to October each year, during the full-moon period. All data collected is used to help manage the elephant population in the park. The trip also includes a visit to a local village outside the park (some of the villagers offer guided walks), and the Okavango Delta, home to Africa's main wildlife species, including the unique lechwe and water buck. Price: pounds 2,495 per person excluding international flights.
The best time for viewing wildlife in Botswana is during the dry season, between May and November, when all the animals come to the water holes. During the rainy season, less wildlife is seen, but the climate is great - hot mornings and dramatic storms in the afternoon.
Botswana High Commission
6 Stratford Place, London W1N 9AE (tel: 0171-499 0031)