Freediving- example of diving accident. The safety partner assurance in freediving required the one up - one down, or one dives and the other was watching him from the surface and assurance on surface too, and if blackout underwater dives and pulls the victim.
To be effective assurance must be good water clarity. Only then underwater blackout can be noticed. The second condition-the bottom has to be on a small (10-15 meter) deep. Example-diving takes place in the Red Sea the coral wall falling down of the large depth (drop-off).
Diver behave cautiously dipped ie not deeper than 15 meters but ... sees a group of very interesting fish, observe and swim. Fishes turns around and lowers the depth. Along with it, our diver descends. After a few seconds longer than 20 meters. Meanwhile minute flow. Freediver decides to return, but the unusual behavior of fish catches his attention again. The computer shows more than two and a half minutes under the water. In a panic, a diver from a depth of approximately 30 meters to the surface moves. Unfortunately, hypoxia, dehydration and fatigue make it 3 minutes after take-off, at a depth of 17 meters unconscious.
Belayer it from the surface of the partner does not immediately realizes what has happened. Moves with the help of just a few seconds. Before arriving at the victim fell 17 meters longer good 8 feet below. When the underwriter finally reaches the unconscious colleague computer shows almost 30 meters. This depth close to its record of life. It is in a panic-diaphragm hurts, ears hurt, not thinking rationally - with a full load trying to pull partner.
After a few seconds, feeling a growing sense of suffocation, terrified partner abandons and flees to the surface. After several seconds recovering. Meanwhile, his partner is in the Big Blue, with no chance of rescue. Impossible? Possible.