One day in Gainesville Florida a group of 5 certified divers decided to explore a freshwater spring. This was to be a routine freshwater spring dive as they had done so many times before.
Although this video was taken a few years ago as part of rescue 911 series, it does a great job at illustrating how easy it is to dive beyond your ability in certain scenarios.
Naturally, diving beyond your ability can easily result in undesired results with even the slightest mishap. Diving beyond your ability is synonymous with diving unprepared.
The story of how this happened is covered in a 2 part video. The first video below explains how the incident happened. The second video explains the cave diving rescue. It is highly informative and covers the thoughts and actions of the rescuer from a rescuer's perspective. (always relevant information)