Huddersfield cave divers' amazing expedition to almost a mile under the earth's surface (Picture gallery)
Intrepid Chris Jewell, 31, of Huddersfield, spent seven weeks navigating the Sistema Huautla cave system in Mexico known as the most remote place ever reached inside earth. Take a look at some of his amazing pictures below.
His group, which was made up of 40 people from around the world, managed to dive, swim, climb and descend through a myriad of pitch black tunnels.
They had the gruelling task of navigating eerie, water-filled abysses known as sumps and at one stage swam underwater in darkness for 600 metres in a 28-metre deep river.
During these dives, the group had no knowledge of where they were heading.
Team member Jason Mallinson, also from Huddersfield, reached the depth of 1,545m, the deepest anyone has been in the Western Hemisphere and the eighth deepest in history.
The group managed to beat the previous record of 1,484m set nearby in the Cheve caves, while the previous record in Sistema Huautla was 1,475m.
The experience is a far cry from Chris Jewell's day job, where he works as an office-based software consultant in Manchester.
For the expedition, Chris managed to negotiate nine weeks unpaid leave, describing it as a once-in-a-lifetime trip.
He said: "You dont know what is happening in front of you but we traced the waters route to a canyon seven miles away.
"We knew where it was heading but we didnt know what was between. It is genuine exploration and it is really exciting.
"We spent up to 10 nights underground at a time, sleeping in the cave and scuba diving flooded tunnels to make it deeper and longer.
"You don't feel the depth underground, but you are aware of the remoteness and that youre two days away from sunlight.
"It is quite tranquil and eerie in places, but it is also very noisy in others because of the fast-flowing river."
The largest underwater sump was 600m long and 28m deep while the last sump reached was 440m long and 81m deep.
Team members came from the UK, USA, Canada, Poland and Mexico, working tirelessly to haul ropes, camping equipment and scuba gear up and down.
First, the cave drivers had to swim 600m underwater through two flooded tunnels to reach their advance camp.
They then spent one week exploring sump 9 and also looking for a way to bypass the flooded tunnel which represents the current end of the system.
It was sump 9 where Jason reached the record depth, with the explorers going without natural light for more than 10 days.
In total, they took 500kg of equipment for the trip, with the group setting off on February 28 this year.
Chris added: "It was incredibly deep and incredibly remote. It was a challenge and adventure and it was physically very demanding.
"Measured from the highest entrance point to the lowest depth, the part we reached was 1,545m deep.
"At the time the depth wasnt the most important thing, we were just pleased we ran a safe and smooth operation.
"It was a bonus that we got the record, we felt fantastic."
Read more: Examiner http://www.examiner.co.uk/news/local-west-yorkshire-news/2013/06/21/huddersfield-cave-divers-amazing-expedition-to-almost-a-mile-under-the-earth-s-surface-picture-gallery-86081-33504506/#ixzz2Z3XdZdKn