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 constantly lose 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 roughly 1%. The Swim skill was thought to also affect how fast you fall through air, but this has [been shown to be incorrect]. It does not affect your falling rate nor your movement speed when falling; however, it may affect your movement when under the effect of the "fly" spell (currently unverified).

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

Special: Warforged do not need to breathe. Their breath bar is not shown and they can remain underwater indefinitely.

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.