Swim

Swim (Str; Armor Check Penalty)
The Swim skill determines how fast your breath bar goes down when you are under water. Once your breath bar is empty you'll start drowning. While drowning you'll lose constantly hit points until you reach the surface or you die. It is therefore a good idea to remove your armor and shield before you dive. Each point in swim increase your swimming speed by 1%.

Special: The Armor Check Penalty is doubled for the Swim skill.

Special: Warforged can stay longer underwater than othe races. Their breath bar empties at a lower speed.

Note: Some sidequests can only be accessed by underwater passages. If you have no or few ranks in this skill it is a good idea to have some potions or magic items around to increase your Swim skill when necessary.