Thom Yorke's idea to do the song for 'Blue Planet II' came whilst he was "half asleep" watching the show.

Thom Yorke

Thom Yorke

Radiohead have teamed up with legendary TV and movie composer Hans Zimmer to record a reworked version of the band's song 'Bloom' to soundtrack the BBC documentary.

The 48-year-old frontman has revealed it was both his curiosity about creatures in the deep sea that are lesser known and his son's desire to help the charity Greenpeace that led to the 'Creep' rockers getting involved.

Speaking to Matt Everitt on BBC 6 Music, Thom said: "This was me lying on the sofa trying to go back to sleep when I've been up too late with my son - 7am when he was small - and it coming in and out of my subconscious.

"And staying there, and you know especially stuff about the deep and these life forms they'd discovered on that series, that seemed to be the implication, that they managed to go so deep that they'd discovered all these creatures that existed that we didn't know about.

"That whole thing for me, the idea of discovering life that humanity doesn't know about, is to me one of the most profound kind of things, profound concepts.

"Even if it's discovering fossils, or the idea that creatures exist - that there's a history to the place we live that we don't know anything about - to me is the most profound, spiritual expression of humanity when we discover it.

"'The Blue Planet' - the original series - was probably the thing, first it turned on my son to the whole thing, and he became obsessed, as you do when you're growing up at that age, five or six, you get all the books and you recite the statistics, all the Latin names, which is what you used to do.

"And then a letter from Greenpeace came through about something or other to the house, and he started reading it and said 'Dad, can we get involved in this'?

'Yeah, sure if you want to."

"So then we established links with Greenpeace.

"Anyway, I got involved in all this stuff over the years, and it started with being half asleep on the sofa watching Blue Planet!"

'Blue Planet II' will air later this year on BBC One in the UK.