Saturation diver Chris Lemons came face to face with every diver’s worst nightmare in September of 2012...
...while working 262 feet below the surface of the North Sea inspecting a drilling structure at a nearby oil field.
Lemons’s support vessel had begun to drift away from the dive site due to a malfunction with its dynamic positioning system.
This caused the umbilical line, which was providing Lemons with air and heat, to snag on something and snap due to the tension.
The boat was now 600 feet away, and Lemons was left alone in the freezing water without heat and only his emergency air supply.
Lemons, thinking quickly and trying not to panic, tried to lie still on the seabed floor in an effort to conserve air.
He knew his emergency tank contained only 10 minutes worth of air, and that hypothermia would likely set in soon after that.
With no lights or communication system and, eventually, with no air left in the emergency tank, Lemons eventually passed out.
Finally, after 38 long and tense minutes, Lemons was rescued by the support vessel, brought safely back to the surface, and revived.
The image of his nearly lifeless "hibernation" remains etched into the minds of his colleagues as a reminder of their dangerous jobs...
The sea turtle is one of the oldest, most intelligent and longest living species known on planet earth.
But in the pitch black waters beneath the island of Borneo, there is dark and secret place that has outmatched the animals.
Some two hundred feet within a gnarled maze of rock formations, there is a cave littered with the skeletons of dead sea turtles.
Pictured here, the graveyard is the the only place like it that is known to exist, and whatever makes it so lethal remains a mystery.
The likeliest explanation would seem to be that turtles simply swim into the cave and are unable to find their way out...
...however, their strong navigation skills and ability to hold their breath for hours would seem to contradict this.
Additionally, amidst the skeletons, several unusual small, translucent yellow shells also litter the sea floor...
...the stillborn eggs of unborn turtles, which are traditionally laid on beaches so that the babies will not drown.
The presence of these eggs had shed no further light on the mystery and adds an inexplicable wrinkle to the foreboding cave.
On February 17, 1944, the U.S. Navy launched Operation Hailstone, a massive attack on the Japanese fleet harbored in Truk Lagoon.
One of the ships battered by U.S. artillery was the Nippo Maru, originally a passenger and cargo freighter built in 1936 in Kobe.
The Nippo Maru was hit with three 500 pound bombs, taking a direct hit it the cargo hold and another to the engine.
Within hours, the massive ship had sunk to the bottom of the lagoon, where it would remain untouched for over two decades...
...when it’s wreck was finally discovered some 160 feet below the surface by famed french oceanographer Jacques Cousteau.
Footage of the eerie shipwreck reveals much of what went down with the ship now preserved in an armor of algae and barnacles.
With the ghost fleet is full size tank on the deck of the ship’s skeleton, it’s decades old metal rusted and jagged.
Creepier still, a pair of gas masks can be found growing out of the wreckage at the front of ship, amidst loose artillery shells...
The picture is a haunting reminder of the war that commandeered this once peaceful vessel and condemned it to the bottom of the sea.
An underwater whirlpool is a phenomenon caused when two opposing currents meet, creating a rotating cyclone of water.
Their appearance verges on the magical, but their power to draw objects into their violent pull is quite real and quite dangerous.
Seen here in 2013, adventurer Jacob Cockle became disoreninted wearing a horse mask to film a whirlpool in Carnsnew, England...
...where old Victorian tunnels dug out in an effort to funnel sand out of the harbor often create spontaneous underwater vortexes.
He took a camera underwater with him to record the huge whirlpool from beneath, something he had previous experience with.
In this particular instance, however, Cockle swam too close to the whirlpool and was drawn helplessly in to its vicious current.
His body was sucked into the 15 foot tunnel of water, pulled through it, and finally was spit out at the other end of the pool.
The dark event and murky end now serves as a warning to those attempting to film similar stunts for fame.
When a human is trapped under water, there are two ways in which the brain responds to an extended period of time with no oxygen.
The first is the bradycardic response, known as the diving reflex, where vessels constrict and the heart slows down...
...allowing blood to be diverted to more vital areas of the body and keeping the submerged human body alive as long as possible.
The second process, hypercapnic vasodilation, involves the body retaining the carbon dioxide that is not being exhaled...
...which in turn causes vessels to dilate and allows cooler blood to enter the brain, vital when one is stuck in cold water.
Both of these processes can help keep a human being alive underwater without oxygen for a shocking amount of time...
...which given the how long it usually takes to safely reach an underwater "survivor," can only be described as a miracle.
Typically, then, the emphasis of Underwater Search and Recovery dive missions is on the recovery of dead weight...
...something this particular rescue team pictured here remains fully aware of, thanks to their nightmarish practice dummy.