The story of the Nutty Putty cave will haunt you

The Nutty Putty Cave is a hydrothermal cave system in Utah that was a popular site for Boy Scouts and other spelunkers. In 2009, it became a grave. John Jones, home for the Thanksgiving holiday, was exploring the cave with friends and family when he took a wrong turn and ended up stuck upside down in a narrow dead-end tunnel.  Over a hundred people worked to rescue John. The rescuers had some success with a pulley system, but a bolt broke off, injuring a rescuer and plunging John further down. 

After twenty-seven hours, John died in the cave. Being upside down for so long likely caused enormous pressure on his lungs and diaphragm and may have also caused his lungs to fill with fluid. Authorities determined it to be too dangerous to attempt to retrieve his body. The landowners were also convinced to seal off the cave using concrete with John's body still inside. In its report on the incident, the National Speleological Society strongly disagreed with both decisions.

If you are claustrophobic, I do not recommend watching this. I am not, but this video still made my heart race.