These spectacular images are a testament to the cave-diving expertise - and sheer fearlessness - of daredevil diver Martyn Farr.
Martyn is the UK's premier cave diving instructor.. He's also, luckily for those of us who prefer to observe danger from a distance, the country's best cave-diving photographer.
In an incredible new feat Martyn, from Crickhowell, Powys, will join an international team next month for a jaw-dropping world record attempt - the longest ever cave penetration.
Martyn plans to record on camera the progress of a team made up of some world's most renowned cave divers as they attempt to delve further into the Pozo Azul cave, near Burgos, Spain, than anyone has ever been before.
Dicing with death every day, 59-year-old dad-of-three Martyn throws himself into some of the most extreme conditions on the planet and happily plunges into uncharted icy cold water - underground, underwater and ALONE.
A death-defying career in the sport spanning nearly 40 years has taken him to every corner of the globe and seen him shattering record after record along the way.
Martyn began cave diving in 1971 and by 1981 had established a world record for underwater cave penetration in the Bahamas.
He is widely admired within the cave diving community for his exploration in Wookey Hole - 1977 and 1982 - and the first traverse of Llangattock Mountain in Wales in 1986.
He has explored caves all over the world, in Iran, Mexico, Borneo, China, Japan, Spain, Greece, Turkey, Brazil, Australia and most recently Russia.
Internationally recognised as a cave and cave diving photographer, with his work appearing in many leading magazines, Martyn has also acted as a consultant for many films and TV programmes.
He has acted as a cave-diving guide for a number of famous faces, notably Princes William and Harry