Greg Foot leads a scientific exploration to the top of the tallest mountain and bottom of the deepest ocean, accompanied by mountaineer medic Dan Martin and oceanographer explorer Leigh Marsh.

Hear more from Greg Foot on his podcast, The Best Thing Since Sliced Bread: http://gregfoot.com/slicedbreadpod/

Watch the incredible Nautilus explorations live: http://www.nautiluslive.org/

Find out more about Extreme Everest: https://www.xtreme-everest.co.uk/

Greg Foot is a science presenter and a regular contributor for Blue Peter. He is fascinated by exploration in extreme environments and has been to both Everest Base Camp and in submersibles 300m deep.

Dan Martin is a mountaineer, medic and the director of the UCL Centre for Altitude, Space and Extreme Environment Medicine. In 2007 he summited Everest and measured the lowest blood oxygen level of any living healthy human (his own!).

Leigh Marsh is the lead communications officer for technology at the National Oceanography Centre (NOC) in Southampton. Her remit includes communicating the development and operations of all of the NOC's robotic and autonomous vehicles for scientific exploration of the deep ocean. She is also a visiting research fellow with the University of Southampton.