A US student spent three days trapped inside a cave after getting lost on a university field trip.
Lukas Cavar, 19, was visiting the Sullivan Cave, in Indiana, last Sunday when he became separated from his classmates.
The Indiana University physics student had left his group in a bid to avoid a section of the cave known as the “backbreaker” - because of its low ceiling - but took a wrong turn.
The teenager’s peers, from the Indiana University Caving Club, then left the gated crevice, locking Mr Cavar inside.
The son of two of the university’s linguistics professors tried picking the padlock with a paper clip to no avail.
Mr Cavar told the the Indiana Daily Student that he began writing “goodbye notes” to his family on his phone and was forced to “come up with a game plan to survive”.
He licked the cave's damp walls to quench his thirst and was left considering foraging for bugs due to a lack of food.
He said: "I was very confused and pretty scared.
"It took me a little while to wrangle my emotions and sort of approach things analytically, sensibly, to come up with a game plan to survive."
Despite screaming for help, Mr Cavar was not rescued until late on Tuesday after his parents filed a missing persons report.
The president of the club returned to the cave and rescued him.
Writing on Facebook after his rescue, Mr Cavar told followers: “Just wanted to let everyone know that I'm safe and sound Boy, it's good to be back on the surface!"
The Caving Club admitted there had been a "failure of leadership” following the incident.
A statement read: “We have a series of rigorous protocols in place that are supposed to prevent situations like this, but they are only effective if followed.
“We had a failure in our leadership to closely follow all these safety procedures."