(With pictures) Editors please note: This feature is under strict EMBARGO until Tuesday February 19.

[STANDFIRST] Joseph Fiennes may be best known for his acting roles - but he's switching up the territory for his latest project, Fiennes Return to the Nile. And it's certainly a moment to cherish, he tells Gemma Dunn.

Joseph Fiennes has long wanted to embark on an adventure with his intrepid explorer cousin, Sir Ranulph Fiennes.

And now, thanks to National Geographic, his dream has been realised.

Fiennes Return to the Nile, a three-part documentary series, will see the actor take the ultimate road trip across majestic Egypt in an action-packed retake of his relative's famous 1969 expedition.

Put through his paces by Sir Ranulph, 74 - who is known as the 'World's Greatest Living Explorer' but he simply calls 'Ran' - Joseph, 48, will face everything from dangerous snakes and spiders to traversing the dunes of the Sahara Desert and tracing mummified bodies.

Considering the pair only met for the first time in the year 2000, it's been a voyage of discovery on both sides, quips The Handmaid's Tale star.

"I had grown up with all these amazing stories of him through my parents, so I was desperate to meet him," he recalls. "[The trip] has made me more respectful of Ran and what he's done and what he's achieved.

"People's legacies are so important, their experiences are so important and the history is so important," Joseph insists. "And that's what I cherish."

So what else is there to know about their epic overland journey?

THE COUSINS FORMED A 'BROTHERLY' BOND

"I was very cautious and nervous because I wanted terribly to get on with Ran. But he's very military, stiff upper lip, so I wanted to break the ice. By the end [of the three episodes] he describes us like brothers. I feel more like a son because he's quite old and I don't want to be thought of as old. That's what I keep telling him, anyway!"

THE FIENNES SHARE FAMILY TRAITS

"We're embarrassingly competitive and, while we don't always share the same sense of one-liner humour, we do share a lot of family DNA and traits. That thing of pushing ourselves. As an actor, generally, you have to push yourself. And despite our differences in age and upbringing - he's very militaristic, ex-SAS. I couldn't be more the opposite, we got on very well."

THERE WERE DANGEROUS MOMENTS

"The [Land Rover] tow rope got wrapped on the front bumper and that was pretty scary. And that's just human error. It was nothing to do with snakes, dehydration or heat exhaustion. It was that someone dropped the ball. It was like a ghost had come and taken the steering wheel and yanked it down. It was out of my control and veered off the road. That was pretty intense."

CREEPY CRAWLIES WEREN'T THE ISSUE

"I don't have any phobias but I am cautious. There was one chap that described the horn viper bite, he said, 'You will bleed through every orifice. Blood will come out of every pore and then you'll be dead in 20 minutes', so I was like, 'OK, that's pretty nasty. I'll try to avoid those'. But I was more scared of not connecting with Ran; he's my cousin and I respect him and his legacy, so I was more nervous about that than being bitten by a horn viper!"

CALM AND STEADY IS KEY

"There's so much advice - not one particular piece - but overall I think it's that sense of calm under very, very intense situations. I don't know if that's inherent or if that's something Ran has to tell himself - to be calm. I'm fascinated about what drives that and that's all to do with his father, a person he didn't know, and a sense of emulating this mythical hero. And the other thing is to prepare yourself and not take risks. Which I was doing all the time."

HE'S YET TO REACH HIS LIMIT

"I don't think I found my cut-off point, which is not a good thing, because that means that they've got to raise the bar! And if I did come close, it was so joyous to be with this legendary cousin that I grew up hearing stories about, and being in Egypt, and being involved in a Nat Geo project, that every time I might have got fearful or reached my limit, it was cancelled out by the sheer joy and luck of being there. It was tough at times. Long, arduous 12-14 hour drives. But just great moments to cherish and pass on to my kids."

HIS CHILDREN APPROVE

"It's only a couple of years ago that they thought I was a pilot in a plane - because I was always flying, they didn't know what I did! And now they love it and I love the fact that this documentary appeals to that young demographic. For me that's really heartening. It's lovely as a dad to show them something that they might learn at school. It's lovely to see them asking questions."

TALK OF HIS NEXT ADVENTURE

"Ran keeps telling me he's got another trip planned if Nat Geo want to do it and it involves lots of cold water... so no! For the moment I am happy with this, but I do love documentaries. Maybe [I'd like] to produce documentaries, but I don't feel driven to do all one thing. If a narrative really appeals to me and I feel really moved by it, then I'll engage. I am loving that this adds a different facet to my work and reveals to people who I am."

Fiennes Return to the Nile will premiere on National Geographic on Wednesday, February 27.