Activate terranium is available as a cantrip to spellcasting classes, and a racial ability to gnomes once per day at first level, and one more every four after that. Any one Terranium derived object within 10 feet of the caster will be activated, causing loaded guns to fire in the direction they or their bearer is facing, to combust, Terrapi to ignite, or 1 TP to become a 30 foot square cloud of breathable steam.
Within the steam cloud Swimmers make a DC 10 Swim check once per round; they swim at their normal speed on a success, or half their normal speed on a failure. Creatures with a swim speed can simply use their swim speed without penalty. Creatures can instead use their land speed to move along the bottom at their normal speed. Creatures walking on the bottom do not pay any movement penalty for walking on sand, stone, or pebble seafloor and only pay 2 squares of movement per square of muck or mud entered (see Marine Dungeon Terrain on page 21). It also negates underwater combat penalties for all melee attacks, although ranged attacks still take the normal underwater penalty. Finally, all within the cloud gain concealment and a -4 penalty on spot checks.