Triumph for Briton after more than two years spent trekking entire length of the Amazon

As the waves of the Atlantic Ocean lapped at his feet in northern Brazil he declared: "It's unbelievable to be here.

"It proves you can do anything – even if people say you cannot. I've proved that if you want something enough, you can do anything."

A few hours earlier, Stafford collapsed at the side of the road, just short of his destination.

But upon arrival at the Maruda beach – and his journey's end – he looked like he had all the energy in the world, as if walking for two-and-a-half years was nothing, as he jumped into the ocean and hugged anyone in sight.

Although he insists he is "no eco-warrior," Mr Stafford said he hoped his feat would raise awareness of destruction to the Amazon rainforest, but that at its heart, it was simply a grand expedition of endurance.

"The crux of it is, if this wasn't a selfish, Boys' Own adventure. I don't think it would have worked," the 34-year-old former army captain from Leicestershire said. "I am simply doing it because no one has done it before."

There are at least six known expeditions along the course of the Amazon river, from its source high in the Peruvian Andes across Colombia and into Brazil before its waters are dumped into the ocean 4,200 miles away. But those used boats to advance their travel.

Mr Stafford and a British friend began the walk on April 2, 2008, on the southern coast of Peru. Within three months, his friend left. Mr Stafford carried on, walking bits of the route with hundreds of locals he met along the way. Eventually, Peruvian forestry worker Gadiel "Cho" Sanchez Rivera, 31, decided to make the journey with Mr Stafford to the Atlantic.

Mr Stafford said he had seen vast swathes of demolished jungle. "It's the people in power who are benefiting from the extraction of the natural resources here," he said. "That's why there are corrupt politicians and laws that aren't enforced."

Despite the devastation, Mr Stafford said he hopes things will change for the better. "I think the average Brazilian is a lot more environmentally conscious than the people in power. I'm optimistic, I'm not pessimistic," he said. He has lived off piranha fish he caught, rice and beans, and store-bought goods found in local communities along the river.

The men have encountered every conceivable danger, from 18-foot caimans, enormous anacondas, illness, food shortages and the threat of drowning.

Mr Stafford said he plans another expedition in September 2011 –

something nobody has ever done – but will not provide details for fear someone might beat him to it.

Until then, a good, long rest awaits. "This expedition has been our lives. For 2/2 years we've done nothing but walk and walk and walk. To wake up the morning after and know that we've done it will be a big change," said Mr Stafford. "I think we'll get used to it though."