A 90-year-old explorer is taking on a marathon challenge to raise funds for rainforest research.

Robin Hanbury-Tenison is riding a water-bike 104 miles down the River Thames from Oxford to Teddington Lock, to raise £150,000 for the Thousand Year Trust.

The trust, led by his son Merlin, plans to use the funds to help build Europe's first temperate rainforest research station on Bodmin Moor.

Hanbury-Tenison will begin the challenge at Magdalen Bridge in Oxford on Friday, June 19, aiming to complete the equivalent of a marathon each day over four days, finishing at Teddington Lock on Monday, June 22 - International Rainforest Day.

The journey marks another adventure for the celebrated conservationist, despite his age.

Hanbury-Tenison told Oxford Mail: "At 90, you work with what you've got... and you keep going."

He has spent decades exploring and protecting rainforests across the globe, but says the UK's own rainforest is almost forgotten.

Hanbury-Tenison added: "I've spent a lifetime exploring the world's great rainforests.

"What many people don't realise is that one of the most remarkable was right here, on our own doorstep and it's almost gone.

"I've seen what we've lost. I've reached an age where I feel, rather urgently, that if I'm going to do something about it, I'd better get on with it."

Britain's temperate rainforest, once stretching along the Atlantic coast, is now reduced to fragmented and degraded patches.

The Thousand Year Trust operates a 250-acre restoration site near Bodmin Moor, home to an ancient oak woodland more than 3,600 years old.

The proposed research station, designed by architects Unknown Works, will include laboratory facilities, a community hub, and a living roof.

It will accommodate up to 12 researchers and support long-term ecological studies.

Merlin Hanbury-Tenison, founder and managing director of the Thousand Year Trust, said: "My father has spent his life fighting for the natural world.

"To see him take on something like this at 90 for a cause we are now building together, is extraordinary.

"This research station will give Britain's temperate rainforest the scientific home it has never had.

"We are asking people to help us make it a reality."

Hanbury-Tenison will be supported by his son and conservation director Harrison Carter in an escort boat, with a film crew documenting the journey.

He has trained for the challenge using an exercise bike and a pond near his home in Cornwall.

All preparatory work for the research station, including legal, design, and planning, has been completed, and construction has now begun.

Donations can be made here.