If lethal damage dice must be rolled for a character who has fallen, they will land in a prone position and loose the remainder of their action for the round (even if no actual lethal damage was taken).
Staggered from a Fall: A character who takes lethal damage from a fall may also be stunned. A successful Fortitude save avoids the effect. The save is a DC 5 for every 10 feet of lethal damage. Failing means the character is Staggered for 1 round. If the save is missed by 5, they are stunned for 1 round instead. If the die roll is a 1, they are stunned for an unknown amont of time (ie GM’s choice).
If a character deliberately jumps instead of slipping or falling, the damage from the first 10 feet of the fall is non-lethal. If they make a successful DC 15 Acrobatics check, the character avoids damage from the first 10 feet and converts damage from the second 10 feet to non-lethal damage. If the Acrobatics check fails, all of the damage from the fall is lethal.
Falling onto Yielding Surfaces: Surfaces such as soft ground and mud converts the first 10’ of damage to non-lethal damage.
Falling into Water: If the water is at least 10 feet deep, the first 20 feet of falling does no damage. The next 20 feet does nonlethal damage (1d3 per 10-foot increment). Beyond that, falling damage is lethal damage (1d6 per additional 10-foot increment).
Characters who deliberately dive into water take no damage on a successful DC 15 Swim check or DC 15 Acrobatics check, so long as the water is at least 10 feet deep for every 30 feet fallen. However, the DC of the check increases by 5 for every 50 feet of the dive.