Good advice

From a web site about skydiving that I came across:

Among the most important skydiving gears you must have is a parachute. Nobody will ever be that bold to jump out of a plane, thousands high up without a parachute to back him up.

No amount of mattresses can save your life with the impact of such a fall. But if it will be your first time to skydive, you should definitely consider some professional help before you skydive.