Small, thickly vegetated islands, each crowned with a mantle of palm fronds, drifted past alternate windows. A herd of lechwe, startled by our helicopter's abrupt appearance, splashed across the shallow floodplain and sent flocks of waterbirds fleeing before them. For the past few minutes our pilot had been zig-zagging, at what seemed a metre off the ground, through a bewildering array of islands. Suddenly we climbed higher and floated there for a moment, the splendour of the Okavango Delta, Botswana's aquatic enigma, spread beneath us.

A thin sheet of water stretched towards both horizons. In the middle distance a deeper pool held a pod of hippos, the gaping jaws of one protesting at our intrusion. Directly below us, the ghostly shape of a crocodile slipped effortlessly through the clear water. Seemingly infinite islands sprouted from the water's surface.

We were hanging over the permanent delta, one of three distinct forms that characterise the Okavango River's remarkable journey in Botswana. Two of the many rivers that start their lives in Angola's Benguela plateau, the Cuito and Cubango, later merge to form the Okavango. There is nothing extraordinary about the river's journey through Angola and along Namibia's Caprivi Strip. Only after it has traversed the Popa Falls and entered Botswana near Mohembo does the Okavango River's metamorphosis to delta begin.

Here the river enters what is known as the Panhandle - a long strip of river and floodplain whose course is set in a south-easterly direction towards the "pan" of the Delta proper. Within its broad confines the river meanders in generous loops before spilling over the Gomare Fault. This fault is the northern boundary of a "graben" or sunken section of the earth's crust that contains the Delta. Below it, the river takes on the appearance of a traditional delta, splitting into an intricate web of channels.

However, the Okavango is not, strictly speaking, a delta at all, but rather an alluvial fan: instead of discharging into a body of water, as an authentic delta does, the Okavango's channels filter into the sands of the Kalahari.

Several other misconceptions surround the Okavango. One is that it is the only "inland delta" in Africa (in fact there are three, one on the Niger River in Mali and another on the Nile River in Sudan). Another is that it is the largest in Africa (it is the smallest of the three).

The fan itself comprises two distinct parts - the permanently and the seasonally flooded areas. The permanent Delta retains water all year round and is clad in a verdant coat of reeds, grasses, shrubs and trees. The seasonal Delta, apart from its main channels, is a grassland area for much of the year, until the annual floodwaters from torrential rains in the Angolan highlands course through the area each winter and transform it, briefly, into a lush wetland similar to the permanent Delta.

Channels, lagoons, islands and forests are the building blocks of the Okavango. The channels are the arteries of the swamps and without the precious water they carry the Okavango would be little more than another large salt pan, like those found further south. Although the channels are always hemmed in by seemingly impenetrable walls of papyrus and reeds, the channel margins are permeable and water constantly seeps into the bordering swamps. These backwaters are home to a multitude of aquatic plant species and the water here is seldom more than knee-deep.

The routes the channels take through the Delta change constantly. The continual deposit of sediment on the channel beds results in increased water loss to the surrounding swamp and allows vegetation to encroach on, and ultimately strangle, the channels. The water eventually flows down paths of lesser resistance (sometimes created by hippos and elephants as they make their way through the swamps) and forms new channel systems, each with an estimated life of 200 years.

This continual process of channel failure is, however, essential to the Delta's health. Each year an estimated 98% of the Okavango's water is lost. The vast majority of this is through transpiration (i.e. "breathing") of the many plants whose by-products are vast amounts of salts and minerals that eventually concentrate in and toxify the soils of the Delta's islands.

As a result, the islands constantly grow as more salts and minerals are trapped between their soil particles. This continual growth takes place on the islands' edges and consequently their interiors are the most toxic, while the periphery remains relatively healthy. Vegetation on the islands grows in distinctive bands depending on its tolerance to the varying toxicity levels. Eventually even the most salt-tolerant plant species are not able to survive. Each time a channel fails it temporarily diverts water from these contaminated areas and allows rainwater to flush the salts and minerals from the islands.

Although for good reason, chroniclers of the Okavango Delta concentrate on its wetlands, an often-overlooked feature is its towering forests. Fringing the larger Delta islands and its dryland edges are extensive tracts of riverine forest. Growing on elevated ridges around the waterways, jackalberries, sausage trees and mangosteens, among others, form high-reaching woodlands as their crowns compete for sunlight. Large herds of buffalo and impala retreat to the shade of the forest canopy during the heat of the day. The forest is also a favourite haunt of leopard.

Beyond the riverine forests grow endless stands of mopane trees. In summer, rainwater pans form in these woodlands, providing water for the herds that converge on them, drawn by the new flush of grasses.

This variety of habitat types enables the Delta and its surrounds to support a remarkable diversity of life forms, including more than 160 mammal, 400 bird, 150 reptile, 80 fish and 5,000 insect species. Even so, the Delta is not considered a prime wildlife region. The apparent lushness of the terrain is deceptive - this is part of the wider Kalahari system. The soils are sandy and poor in nutrients; hence the plant communities are not as productive as one might expect and the carrying capacity of the grasslands is much lower than that of such wildlife havens as the Serengeti-Mara. Only in Moremi Game Reserve and the surrounding private concessions do the game populations reach densities comparable to those of Africa's other major sanctuaries.

With the exception of the much-persecuted rhino, the "Big Five" are well represented here and it is one of the better places in Africa to see leopard and wild dog. Unlike most other African game sanctuaries, however, the Okavango is never crowded. Happily absent is the scourge of East African reserves - those scores of minibuses crowding around hapless predators.

Botswana's Department of Wildlife & National Parks (DWNP) has adopted a low-volume, high-cost policy that is extremely well implemented. Numbers of guests at lodges and tourists in public campsites are strictly controlled. It is unlikely that you will see more than five other vehicles during any game drive in Moremi. This is especially the case in the private concessions where camps rarely hold more than twenty people and the number of vehicles at any sighting is generally limited to two.

For those who prefer to explore the Okavango in style, the range of options is unlimited. Maun, situated at the base of the Okavango, is the gateway to the region and the headquarters of the safari industry. Rapidly changing from its legendary dusty frontier town image, it now boasts several hotels, a number of large retail stores and one of the busiest airports in the southern hemisphere. Small bush planes constantly ferry visitors to and from the many lodges that cover the Delta.

Visitors will have a chance to explore both wet-and dry-land Okavango. Most lodges within the Delta are luxury tented camps and, depending on their location, offer a combination of guided walks, game drives and trips by mokoro (dugout canoe) that focus on game-viewing, bird-watching or angling.

Taking an excursion on a mokoro is the quintessential Delta experience. The dugouts sit low in the water with barely five centimetres between the top of the vessel and the water surface. The only sounds are those of the Okavango accompanied by the rhythmic flow of water as your poler propels you over the floodplains. A number of lodges have recently begun using fibreglass imitation mekoro (plural of mokoro), as increased demand for the craft has led to overharvesting of large trees like jackalberries, traditionally used in their manufacture.

For those who decide to explore the region independently, self-drive visitors to the Okavango are restricted to Moremi Game Reserve and the various lodges spread along the western edge of the Panhandle. Although wildlife is not prolific in the Panhandle, as man has long inhabited the region, it is possibly the best region in the Delta for birdwatching.

Among the more untamed areas in Africa where you can camp is Moremi Game Reserve. Although there are designated campsites spread throughout the reserve, they are not fenced and animals regularly visit camps at night. Third Bridge campsite is notorious for its nocturnal lion visits. The campsite takes its name from the mopane pole bridge that fords a nearby Okavango channel. Rather than swimming through the crocodileinfested-waters, the resident lion pride has taken to crossing the bridge. Game-viewing can therefore be done from the comfort of your campsite.

In line with the DWNP's low-volume, high-cost policy, camping fees in Moremi Game Reserve are the most expensive in southern Africa. The resultant lack of overcrowding, however, makes for a far better wilderness experience.

Like wilderness areas throughout the world, the Okavango Delta is under constant pressure. That it has arrived at the latter half of the twentieth century in such a pristine state is quite miraculous. Veterinary cordon fences, over-utilisation of natural resources, and water-poor Namibia's intention to siphon water from the Okavango River before it reaches the Delta, are just some of the perils it faces. While most of the threats have been acknowledged and are currently being investigated, there is certainly evidence to suggest that the veterinary fences, by protecting it from further development, have done the Delta as much good as harm.

The Okavango Delta remains, however, one of Africa's most unsullied and serene destinations. Apart from its Edenesque scenery and wildlife, it offers what few others do - a true wilderness experience.

Adrian Bailey spent more than a year in the Okavango Delta gathering material for his book, Okavango - Africa's Wetland Wilderness. He is a BBC Wildlife Photographic Competition winner.

Delta Animals

The Okavango Delta hosts a remarkable diversity of life forms including one of the continent's largest intact elephant populations. With the exception of the two rhinoceros species, the vast majority of animals typically seen on African safaris are well represented here. Among the prime wildlife quarries of the Okavango are:

The Sitatunga

Tragelaphus spekei

The Delta is the southernmost limit to the range of the sitatunga, a semi-aquatic antelope that survives largely on the papyrus edge that colonises large parts of the Delta. Its 18cm long, splayed hooves enable it to move with ease through reedbeds, although this adaptation means that only the fortunate few will catch a glimpse of this elusive creature.

The Wild Dog

Lycaen pictus

The Okavango is arguably one of the best places in Africa to see Wild dogs. It hosts one of the largest remaining populations of these fascinating but highly endangered carnivores and the Botswana Wild Dog Project, currently busy with essential research into the conservation management of the species, is based on the Delta's southern edge.

Pel's Fishing Scotopelia peli

Undoubtedly the biggest birding tick of the Okavango is the large, ginger-coloured Pel's fishing owl. It is totally nocturnal and daylight sightings are usually of a flash of ginger soaring through thick riverine forest, its preferred habitat. The best chance of seeing one is usually at night in the Panhandle, when they hunt from regular perches overhanging prime fishing spots.

The Slaty Egret

Egretta vinaceigula

The slaty egret is one of the world's rarest herons. It is largely confined to and breeds solely in the Okavango. It was only finally recognised as a valid species in 1971 and, as yet, little is known about the bird, except that its future is precariously linked to that of the Delta.

Rhythm of the Waters

The Okavango Delta is a remnant, along with the Makgadikgadi Pans, of a huge inland lake that covered a large part of Botswana thousands of years ago. Eventually a series of parallel faults, extensions of the East African Rift System, formed across the Okavango River and the sinking of a section of the earth's crust between these faults interrupted the river's flow, gradually leading to the desiccation of the ancient lake.

Over time, this trough filled with an accumulation of sediment and wind-blown debris. This retarded the river's flow further, and led to the forming of the Okavango's alluvial fan - the confusion of meandering channels, forested islands and lagoons of the Okavango Delta as we know it today.

What makes the Delta such a miraculous place, lying as it does within the Kalahari (the largest continuous stretch of sand in the world) is a subtle rhythm of water. The first arrives as rainfall during summer, with pans forming throughout the Okavango's towering woodlands, providing drinking water for the herds that gather there to feed on the fresh grasses. As winter approaches, these pools slowly dry and leave behind cracked husks.

Just when animals throughout southern Africa begin their struggle to survive until the next rains, the Okavango's animals are blessed with another coming of water. The tortuous Delta channels slow the annual floodwaters from Angola. Thus, instead of passing through the area within a fortnight, as it would were there no Delta, the waters take several months to make it to the Okavango's edge, arriving there in the middle of the dry season.

This new inundation covers the seasonal Delta's grasslands with a thin layer of water, providing both breeding grounds for fish and feeding grounds for birds. Later, as these waters retreat, a flush of new grass is revealed which sustains the region's herbivores for the rest of the dry season.

Okavango Delta Factfile

Status: The IUCN lists the Okavango Delta as a natural site of World Heritage quality, with the following Universal Significance: "This inland delta supports one of the richest faunas in southern Africa, forming a permanent source of water in the midst of arid habitats; it is comparable only to Sudan's Sudd as an important wetland. It has its source in the Angola highlands, with internal drainage. It supports, among many others, hippo, sitatunga, sable, roan, elephant, and crocodile, as well as migratory birds and, in particular, waterfowl populations of outstanding interest, such as slaty egret, a species of very restricted distribution elsewhere. The site is now seriously threatened by endosulphan pesticide spraying aimed at eradicating the tse-tse fly."

Access: The town of Maun is the hub to the region. Many international airlines fly into Maun, and all air charter companies operate from the town. Road access to Maun from Francistown, Ghanzi or Victoria Falls is good, but you will need to transfer to your lodge by air.

Accommodation: There are a good number of private lodges and camps throughout the Delta. All are of a very high standard and most are tented with full en suite facilities and a swimming pool.

These include:

Camp Okuti: 20 beds; Xudum Camp: 16 beds; Rann's Camp: 16 beds; Mackateers: 8 beds, horse safari camp; Chitabe: 16 beds; Walking Trails: 8 beds per 3 camps (2 tree-house, one fly camp); Delta Camp: 16 beds, plus exclusive Sitatunga Trail; Oddball's: base for mokoro trails; Mombo Camp: 20 beds; Xigera Camp: 16 beds; Nxabega Okavango Safari Camp: 18 beds; Camp Okavango: 22 beds, one suite; Camp Moremi: 22 beds; Sandibe: 16 beds; Xugana Island Lodge: 16 beds; Xugana Mokoro Trail: six people, mobile operation; Tsaro Elephant Lodge: 16 beds; Gunn's Camp: 14 beds; Xakanaxa Camp: 24 beds; Khwai River Lodge: being renovated to cater for 24 beds; Eagle Island Camp: 24 beds; Crocodile Camp: 20 beds; Semetsi Camp, 16 beds; Gomoti Camp: 16 beds; Abu Camp: elephant back safaris; Machabe Camp; Shindi Island; Pom Pom; Island Safari Lodge; Okavango River Lodge; San-Ta-Wani Safari Lodge; Drotsky's Cabins.

Ask your African travel specialist for details on all of the above properties.

Rates: Expect to pay between US$240 and US$400 per night; average US$300.

Best Time: Game viewing is at its best when the flood plains are inundated, usually between June and October / November.

Further Reading: Okavango: Africa's Wetland Wilderness, by Adrian Bailey; Kalahari: Life's Variety in Dune and Delta, by Michael Main; Okavango: Sea of Land, Land of Water, by Anthony Bannister; plus most guide books on the birds and mammals of southern Africa.

Published in Travel Africa Edition Four: Summer 1998. Text is subject to Worldwide Copyright (c)