The Brazilian pantanal, the world's largest freshwater wetland

Established as a World Heritage Site in 2000, the Pantanal of Brazil, Bolivia and Paraguay is easily one of the top five places in the world to see wildlife in its natural environment.

From December to March, run-off from seven rivers transforms this 210,000 sq km area into an immensely productive wetland half the size of France. Then, starting in June, the tide literally turns as the waters begin to recede, trapping many of the region's 600 fish species in increasingly smaller ponds, lakes and channels. From July to December, the wildlife viewing is extraordinary as ever-growing numbers of animals gather around shrinking bodies of water to drink and feed on the huge quantities of trapped fish, producing a concentration of fauna not often witnessed in the New World.

This is when wading birds - ten species of heron and egret, three species of stork, and six species of ibis and spoonbill - begin nesting in gigantic, noisy colonies that can cover square kilometres. And almost more impressive is the sight of the region's 20 million black caimans amassing around every water hole, reaching densities of 150 caimans per sq km (the highest levels in the world).

Equally drawn to water holes are capybaras, anacondas (reaching up to 7m in length), marsh deer and jaguars; but do not overlook the fact that this entire unique region is fabulously rich in wildlife. What distinguishes the Pantanal ecologically is that it combines elements of central Brazil'scerrado savannahs and Paraguay's chaco scrublands - along with an endless maze of ponds, lakes, rivers, forests and islands - to create a habitat for 200 species of mammal and 650 species of bird.

The Pantanal has few people and no towns. Distances are so great and ground transport so poor that people get around in small airplanes and motorboats; 4x4 travel is restricted by the seasons. The seasonal flooding has also made systematic farming impossible and has severely limited human incursions into the area. Instead, it provides an enormously rich feeding ground for wildlife.

The best way to approach the Pantanal is along the Transpantaneira Road, which dries out in July long enough that you can drive (or cycle) the 150km from Poconé near Cuiabá, south to Porto Jofre on the Rio Cuiabá.

Information taken from BBC Travel