Grand tours: Don't look now, there's an alligator in our bath

Adventures in literature: the botanist Alexander von Humboldt describes a daunting encounter in the South American interior

The German botanist Alexander von Humboldt (1769-1859) was, according to Darwin, "the greatest scientific traveller who ever lived". With the help of the French botanist Aimé Bonpland, Humboldt made a five-year expedition from Caracas and then along the Orinoco and Amazon, covering more than 6,000 miles in the uncharted New World on foot and horseback and by canoe, while living mainly off cacao beans and river water. Humboldt's travels in South America provided him with material for one of the most ambitious scientific studies of the natural world.

In the Mesa de Paja, in the ninth degree of latitude, we entered the basin of the Llanos. The sun was almost at the zenith; the earth, wherever it appeared sterile and destitute of vegetation, was at the temperature of forty eight or fifty degrees. Not a breath of air was felt at the height at which we were on our mules; yet, in the midst of this apparent calm, whirls of dust incessantly arose, driven on by those small currents of air, that glide only over the surface of the ground, and are occasioned by the difference of temperature, which the naked sand and the spots covered with herbs acquire. These sand winds augment the suffocating heat of the air. Every grain of quartz, hotter than the surrounding air, radiates heat in every direction; and it is difficult to observe the temperature of the atmosphere, and the variable decrement in the temperature of the different strata of the air, the horizon in some parts was clear and distinct; in other parts it appeared undulating, sinuous, and as if striped. The earth there was confounded with the sky. Through the dry fog, and strata of vapour, the trunks of palm trees were seen from afar. Stripped of their foliage, and their verdant summits, these trunks appeared like the masts of a ship discovered at the horizon.

There is something awful, but sad and gloomy, in the uniform aspect of these Steppes. Every thing seems motionless; scarcely does a small cloud, as it passes across the zenith, and announces the approach of the rainy season, sometimes cast its shadow on the savannah ...

No sooner were our instruments unloaded, and safely placed, than our mules were set at liberty, to go, as they say here, "and search for water in the savannah". There are little pools around the farm, which the animals find, guided by their instinct, by the scent of some scattered tufts of mauritia, and by the sensation of humid coolness, caused by little currents of air amid an atmosphere, which to us appears cool and tranquil. When the pools of water are far distant, and the people of the farm are too lazy to lead the cattle to these natural watering places, they confine them during five or six hours in a very hot stable, before they let them loose. Excess of thirst then augments their sagacity, sharpening as it were the senses and their instinct. No sooner is the stable opened, than you see the horses and mules, especially the latter, the penetration of which exceeds the intelligence of horses, rush into the savannahs. Their tail raised, their head thrown back, they run against the wind, stopping from time to time as if they were exploring space; they follow less the impression of sight than of smell; and at length announce by prolonged neighing that there is water in the direction of their course ...

We followed our mules in search of one of those pools, whence the muddy water was drawn, that had so quenched our thirst. We were covered with dust, and tanned by the sandy wind, which burns the skin still more than the rays of the Sun. We longed impatiently to take a bath, but we found only a great reservoir of feculent water, surrounded with palm-trees. The water was turbid, though to our astonishment, a little cooler than the air. Accustomed during our long journey to bathe whenever we had an opportunity, often several times in the same day, we hastened to plunge into the pool. We had scarcely begun to enjoy the coolness of the bath, when a noise, which we had heard on the opposite bank, made us leave the water precipitately. It was an alligator plunging into the mud. It would have been imprudent to pass the night in this marshy spot.

We were only at the distance of a quarter of a league from the farm, yet we continued walking more than an hour without reaching it. We perceived too late, that we had taken a false direction. Having left it at the decline of day, before the stars were visible, we had gone forward in the plain as by chance. We were, as usual, provided with a compass, and it was even easy for us to steer our course from the position of Conopus and the Southern Cross; but all these means became useless, because we were uncertain whether, on leaving the farm, we had gone toward the East or the South. We attempted to return to the spot where we had bathed, and we again walked three-quarters of an hour, without finding the pool. We sometimes thought we saw fire at the horizon; but it was the stars that were rising, and of which the image was enlarged by the vapours. After having wandered a long time in the savannah, we resolved to seat ourselves beneath the trunk of a palm-tree, in a spot perfectly dry, surrounded by short grass; for the fear of water serpents is always greater than that of jaguars in Europeans recently disembarked. We could not flatter ourselves that our guides, of whom we knew the insuperable indolence, would come in search of us in the savannah before they had prepared their food, and finished their repast.

ln proportion to the uncertainty of our situation, we were agreeable affected by hearing from afar the sound of a horse advancing toward us. The rider was an Indian armed with a lance, who had just made the rodeo or round, in order to collect the cattle within a determinate space of ground. The sight of two white men, who said they had lost their way, led him at first to suspect some trick. We found it difficult to inspire him with confidence; he at last consented to guide us to the farm of the Cayman, but without slackening the gentle trot of his horse. Our guides assured us, that "they had already begun to be uneasy about us" and to justify this inquietitude, they gave a long enumeration of persons, who, having lost themselves in the Llanos, had been found nearly exhausted. It may be supposed, that the danger is imminent only to those who lose themselves far from any habitation; or who, having been stopped by robbers, which has happened of late years, have been fastened by the body and hands to the trunk of a palm tree.

This extract was taken from 'The Faber Book of Exploration', edited by Benedict Allen (£25, hardback), which is available to Independent on Sunday readers for £22.50 (including p&p within the UK). To order a copy call 01256 302692 and quote 'The Independent on Sunday'.

Follow in the footsteps

Follow the river

The Orinoco is the longest river in Venezuela. Forming the south-eastern border of the vast Llanos region, it runs through the Delta De Orinoco to the Caribbean.

Sparsely populated and seldom visited, most of Los Llanos is divided into large cattle ranches called hatos. Some are turning to ecotourism: the intrepid traveller can witness authentic bull-grappling rodeos, and Joropo – the flamenco-descended musica Llanera.

There are about 350 species of bird in Los Llanos, including the scarlet ibis. Mammals include dolphins, jaguars, crocodiles, and the 120lb capybara – the world's largest rodent.

Guanare is Venezuala's spiritual capital and home to the country's patron Saint, La Virgen de Coromoto.

Getting there

Los Llanos is accessible in both the wet and dry seasons. There may be some flooding between November and May, but this cooler wet season brings out the wildlife. Journey Latin America (020-8747-3108; www.journeylatinamerica.com) offers a 10-day tour of Venezuela's highlights for £2,471, including return flights, transfers, accommodation, and most meals. The tour includes a trip to Salto Angel waterfalls, three nights on a ranch in Los Llanos, a safari, river excursions, and trips to two Indian villages.