DESCRIPTION

A wall of water spell creates a barrier of surging water. Any creature forced into or attempting to move through a wall of water must make a DC 20 Swim check. Success means the creature can swim through the wall as normal for that sort of movement. On a failed Swim check, the creature takes 1d3 points of nonlethal damage from the violent currents within the wall and cannot move.

A creature within or on the opposite side of a wall of water has total cover against opponents on outside or on the other side of the wall unless those opponents have freedom of movement effects. Magical effects are unaffected except for those that require attack rolls (which are treated like any other effects) and fire effects.

Nonmagical fire (including alchemist's fire) does not burn within or through a wall of water. The wall of water blocks line of effect for any fire spell. If the caster has made the caster level check to make the fire spell usable underwater, the surface still blocks the spell's line of effect.

Casting spells within a wall of water is difficult. If the caster cannot breathe water, he must make a DC 20 concentration check. If the caster can breathe water, he must make a DC 15 concentration check. This is in addition to the caster level check to successfully cast a fire spell underwater, if applicable.

Spells or spell-like effects with the fire descriptor used within a wall of water are ineffective unless the caster makes a caster level check (DC 20 + spell level). If the check succeeds, the spell creates a bubble of steam instead of its usual fiery effect, but otherwise the spell works as described. A supernatural fire effect is ineffective underwater unless its description states otherwise.

You can make the wall as thin as 5 feet thick, which allows you to shape the wall as a number of 10-by-10-by-5-foot blocks equal to twice your caster level. This has no effect on the Swim DC for moving through or within the wall.