The lancha rapida speeds through a narrow channel – a shortcut in the flooded jungle – en route to a floating attraction where guests can touch the velvety skin of pink dolphins.

Clapboard stilt homes with acai palms in their yards, centenarian ceiba trees, egrets and an occasional eco lodge flash by as the launch jets up river in the pelting rain before entering Lake Acajatuba where the rare, fresh-water dolphins are waiting.

The rustic dolphin encounter is run by a family who live aboard an adjoining barge. Tourists, who stand on a submerged platform as several dolphins approach to eat chunks of raw fish, marvel at their rosy colour.

Officials in Manaus, the capital of the state of the Amazonas, would like to see many more such visitors and hope Manaus' turn as a World Cup host city will help boost tourism to the city and the rainforest beyond.

But there's a delicate balancing act between opening up the Amazon region to more tourism and preserving the environment and resources that make it so magnificent.

"Too much visitation can play against you," says Ronald Sanabria, the Rainforest Alliance's vice president of sustainable tourism.

From the air, rainforest trees look like giant heads of broccoli and they stretch as far as the eye can see. But the area has already lost about 15 per cent of its forest cover due to logging, dams, oil and gas pipelines, agriculture, roads and mining projects.

Contamination of the rivers that snake through the Amazon Basin also puts the region's diverse ecosystems at risk.

Even though the government considers encounters with pink dolphins, known locally as botos, to be among the greatest tourism attractions in the Amazon, their numbers have been declining dramatically in recent years.

Fueled by an appetite for piracatinga – the vulture catfish – in neighbouring Colombia, local fishermen have been using pink dolphin flesh as bait. In an effort to protect the pink dolphin, in early June Brazil's Fishing and Aquaculture Ministry announced a five-year fishing ban on piracatinga. The moratorium is expected to go into effect in early 2015.

The World Wildlife Fund says that contamination of rivers and lakes as well as dams that fragment freshwater dolphin populations are also threats.

At the dolphin attraction in the middle of Lake Acajatuba, the dolphins swim freely and approach when a trained handler heads to a submerged platform with a small group of tourists and brings out the fish. Only the handler is allowed to feed them and handouts per dolphin are limited to about 10 per cent of their daily consumption.

Encounters are limited to 10 to 15 small groups a day, so the dolphins don't become stressed.

Brazil's Institute for the Conservation of Biodiversity said dolphin attractions have gradually adopted such protocols developed by wildlife experts but emphasised they are just rules at this point and "are not yet considered laws."

The Institute views interaction with the dolphins as a way of promoting conservation.

Meanwhile, the pink dolphins, which can grow up to almost 3 metres in length and weigh as much as 136 kilos, continue to occupy a special place in the folklore of the Amazon.

"People say the botos have the ability to come out of the water and take the shape of a man and dress in clothes," said Gilton Barbosa Macuje, a regional tourism guide. "The boto is always dressed in white and he wears a hat to cover the blowhole on his head.

"People say he is very handsome. All the women in the village follow him and he chooses one to follow him back into the water," said Macuje. Later, he said, the woman returns with a big belly and the story is that the dolphin got her pregnant.

But despite the dolphins' perceived magical powers, they remain vulnerable. WWF is currently doing river dolphin surveys that aid in determining their status and help with research, and also has an adopt-a-pink-river-dolphin program to provide support to protect them and their habitat.

Although it's become somewhat lost amid news about delays in finishing soccer stadiums and World Cup-related protests, Brazil has made an effort to have a green World Cup. Among its initiatives is promoting sustainable tourism.

The Rainforest Alliance notes that Brazil is a favourite to win the World Cup but it's also a "winner when it comes to sustainability and biodiversity."

The Alliance – working with the Sustainable Amazon Foundation and the Community-based Tourism Forum of the Lower Rio Negro – also is helping out by offering training in sustainable practices to hotels, eco lodges and other tourism-oriented business in six communities in the Baixo Rio Negro where the river meets the rainforest.

One of the success stories is the Pousada Garrido in Tumbira, says Sanabria.

The pousada (lodge) is run by Roberto Brito de Mendonca, who used to earn a living illegally cutting timber in the Amazon. Now his lodge, which recycles and uses solar energy, has become a favourite among bird watchers. One of the local guides has learned to mimic the calls of 32 Amazonian birds.