Mercedes, Argentina - Part of the adventure was getting there. Our off-road vehicle jolted along the dirt road from the small city of Mercedes to the Ibera wetlands in north-eastern Argentina's Corrientes province. After 120 kilometres, plenty of potholes and even more patience, we reached the hamlet of Colonia Carlos Pellegrini, gateway to Esteros del Ibera, a vast amphibious nature reserve teeming with flora and fauna.

"In the language of the Indians, 'Ibera' basically means 'gleaming, glowing, shining water,'" said Jose Martin, our Argentine tour guide. From a gaucho family, Martin still speaks Guarani, the language of the region's aboriginal inhabitants. It is spoken deep in the throat and sounds somewhat gurgled.

The surface of the water really did sparkle and glitter as our motorboat turned into the Ibera Lagoon. A world of marshes, lagoons and floating islands, it seemed like a waterlogged Garden of Eden. The wetlands cover 1.3 million hectares, an area five times larger than the German state of Saarland.

Cormorants and vultures, among Ibera's more than 350 indigenous bird species, took wing. The wetlands are not a magnet for bird watchers from around the world for nothing. A 1.2-metre-tall jabiru, a bird species considered to be endangered, clearly stood out in the green surroundings with its white plumage, black head and red throat pouch.

"I used to hunt birds. It was our tradition," Martin remarked. Hunting is now banned, and some former hunters have become conservationists. Martin has even created a private nature reserve with a subtropical forest.

"Indians used to live on the islands that slowly drift in the water," he said. Up to several hectares in area and two metres thick, the "islands" - floating mats of grasses, reeds and small trees as well as delicate water hyacinths, lilies and orchids - are a lush habitat for numerous bird species.

Our boatman switched off the motor and propelled the vessel quietly by using a wooden pole to push off the bed of the shallow lagoon. A wide-eyed marsh deer looked at a battery of cameras pointed toward it and then went on feeding. Many animals allow themselves to be observed at close range without fleeing.

A family of capybaras swam by, constantly munching grasses as they went. Just a few metres away lurked a caiman, one of the giant rodents' chief predators. Our boat approached the reptile, whose mouth - pink-coloured and studded with pointy teeth - was wide open. The cameras clicked incessantly.

The next caiman, an imposing specimen nearly three metres long, also lay motionless on the bank. One of its hind feet rested nonchalantly on its back, yoga-like. Suddenly, in a fraction of a second, it burst into motion and vanished in the underbrush.

"I can hardly believe that you don't have to share this natural spectacle simultaneously with thousands of other tourists, like at nearby Iguazu Waterfalls," commented Ian Argyle, an Englishman. Then he took another photo, this time of a tangled black mass on a branch. It turned out to be a colony of hundreds of spiders protected by an impenetrable white web as tough as nylon.

Lory Perea Munoz is one of the pioneers of nature tourism in the Esteros del Ibera. "The lagoon radiates a rare magic," she said. An Argentine, she operates the Posada Aguape, one of the oldest lodges in Colonia Carlos Pelligrini. It organizes wildlife-watching outings for its guests. But Munoz is afraid that soft tourism could turn into mass tourism if the access road is tarred.

Sofia Heinonen, a 40-year-old biologist, is worried about this too. She advocates making Ibera a national park. "But that could take years," she said.

Her Cessna took off, and the vastness of the wetlands came into view from the air. "The ecosystem is fed solely by precipitation. That's why it is so important as a freshwater reservoir," Heinonen said and pointed downward. Rice farmers were spraying pesticides, one of the threats she is doggedly battling.

A night-time boat trip offers a quite different look at nature. "Many animals are nocturnal," explained Pedro Noilles, who works at the Ypa Sapukai Lodge. When his boat cast off shortly before midnight, lamps illuminated the bank area. The nature tourists on board expectantly followed the beam of light.

What they soon spotted were small points, as red as the fire in an Argentine grill, moving in pairs on the surface of the water. They were the eyes of swimming caimans, fascinating and fearsome.

INFO-BOX: Ibera Lagoon

GETTING THERE/TRAVEL DOCUMENTS: Several bus companies offer overnight service from the Argentine capital Buenos Aires to the small city of Mercedes, 740 kilometres away. A taxi then takes travellers a further 120 kilometres over a dirt road to Colonia Carlos Pellegrini. European Union nationals do not need a visa for stays in Argentina not exceeding 90 days. Passports must be valid for at least three months beyond the planned date of departure from Argentina.

CLIMATE: North-eastern Argentina is warm and humid, and its most pleasant seasons are autumn and spring.

HEALTH: It is advisable to be vaccinated against polio, tetanus, diphtheria and hepatitis A.

INTERNET: www. esterosdelibera. com, www. iberaesteros. com. ar (dpa)