He previously detailed how he was nude when he proposed to his wife Shara and is a big fan of skinny dipping.
"I pulled out the ring from my butt cheeks," he told Piers Morgan in 2014.
"She was standing there going, 'What are you doing?' She was in a towel and a massive Atlantic roller came and I went, 'Will you' and it … took me up the beach.
Bear Grylls is known for his love of skinny dipping. Photo / Supplied.
"I had all the seaweed and I was spinning around, so I tried it again and, and in this sort of moment of heavy sedation, she said, 'Yes.'"
Grylls also touched on his love of swimming naked, saying: "If there's a substantial body of water around and nobody's looking, I'm often quite tempted to strip off and dive in."
The former SAS soldier also once sent a naked picture of himself to fellow TV star Dermot O'Leary before taking a dip in the ocean.
"We own this little island in north Wales and there's a great cliff jump into the sea and I do this every morning to be honest when I'm up there and before anyone's out," he explained.
"But the thing is with this photograph, I looked at it on my iPhone and when I texted it looked fine, sent it to him. And actually if you do blow it up, you can just see the end of what I didn't realise was visible, so yes, that's the danger of small screens on iPhones.
"Can I say it was an incredibly cold winter's day a week ago."
