When attempting a high fall (over twenty feet) into water in an emergency situation, you will not know much about your surroundings, specifically the depth of the water. This makes jumping particularly dangerous.
If jumping from a bridge into a river or other body of water with boat traffic, try to land in channel - the deepwater area where boats go under the bridge. This area is generally in the center, away from the shoreline.
Stay away from area with pylons that are supporting the bridge. Debris can collect in these areas and you can hit it when you enter the water.
Swim shore immediately after surfacing.
HOW TO JUMP
1. Jump feet first.
2. Keep your body completely vertical.
3. Squeeze your feet together
4. Enter the water feet first, and clench your buttocks together.
If you do not, water may rush in and cause sever internal damage.
5. Protect your crotch area by covering it with your hands.
6. Immediately after you hit the water, spread your arms and legs wide and move them back and forth to generate resistance, which will slow your plunge to the bottom.
Hitting the water as described above could save your life, although it may break your legs.
If your body is not straight, you can break your back upon entry. Keep yourself vertical until you hit the water.
Do not even think about going in headfirst unless you are absolutely sure that the water is at least twenty feet deep. If your legs hit the bottom, they will break. If your head hits, your skull will break