Wood Wall Topple it to create a raft.
Mold Walls This spell is good for sealing up underwater habitats.
Location Knowing the location of two points combined with advanced math allows the character to triangulate his position. The limited range primarily allows for underwater navigation within a limited area.
Lights Way: Any light spell would be useful in the water and absolutely necessary in under 150 feet. (The depth below which normal vision is impossible will vary greatly based on the clarity of the water).
Consider all light spells to have half the range with a maximum potential of 300 feet.
Waterrunning With spell mastery it can be used under water.
Purifications: Some of these spells may be essential for long term sea voyages or for carrying your sandwich underwater.
Poison Resistance Adds to resistance against the bends and nitrogen narcosis.
Unpoison Can be used to remove nitrogen in the blood to cure nitrogen narcosis and the bends.
Blood Law: Vessel repair spells can be used to cure a patient of the bends (severity determines if it is minor or major). This does not cure damage done to the brain or heart due to an embolism.
Hold Kind If a target is not positively buoyant and is treading water or swimming, then they will sink.
Mnr Brain Repair Can be used to cure any brain damage due to an embolism (due to the bends).
Heart Repair Can be used to cure any damage done to the heart due to an embolism.
Pathfinding Can be used to find channels or navigable waterways.
Merge Organic Dont forget that coral is organic but it may be difficult to find a contiguous piece large enough to fit in. While merged, you dont have to breathe.
Freeze Liquid Ice is always positively buoyant compared to the water it was made from.
Natures Summons: The choice of animals used on this list should be entertaining. We suggest that any Ranger in service to an ocean deity should have great leniency on this list including changing Tornado Prayer into Whirlpool Prayer and so on.
Path Lore If cast on a sea trade route, then you can learn the nearest stop on the way.
Conveyance Without a doubt, this is the best way to explore areas underwater, but only up to 150 feet deep. While this spell allows for great lateral exploration, at that depth it becomes too dark to see. No other spells may be cast while this spell is in effect. If sense enhancement spells are cast prior to conveyance, this limitation may be circumvented (assuming the GM interprets the spells in such a way as to allow this).
Staying This spell has greater efficacy in the water where small amounts of pressure can affect the buoyancy of an item. This spell can be used to keep naturally buoyant objects underwater or to keep negatively buoyant objects at the surface.
Hurling Maximum range is ¼ and range penalties scale appropriately.
Essence Perceptions These spells can be used to explore the underwater near the surface. This is an excellent way to guide a ship through shoals or other treacherous reefs.
Invisible Ways Invisibility works fine underwater. Be sure to note that swimming displaces water and causes mini-turbulences that can be detected at close range.
Change to Kind It never hurts to shape change into a more versatile water form.
Merging A target can be merged into a solid form either positively or negatively buoyant and safely transferred up or down. This assumes there is a safe exit point at the bottom of the ocean.
Lofty Bridge Flying spells do not work underwater.
Shock Bolt Salt water will conduct the electrical charge away from the source very rapidly in all directions. This limits the range of all electricity bolts. Maximum range is reduced to 10 feet and gains no range bonus. Caster and all within 10 feet of the caster take 1d10 damage (including the target). If caster touches the target, then he gains +35 to the attack.
Lightning Bolt Maximum range is reduced to 30 feet and gains no range bonus for under 10 feet. Caster and all within 30 feet take 3d10 damage (including the target). If caster touches the target, then he gains +35 to the attack.
Tremors This spell can cause tidal waves. Use with caution.
Boil Liquid All in the area of effect take an "A" heat crit.
Warm Solid Prevents hypothermia.
Heat Solid See "Boil Liquid"
Fire Bolt Maximum effective range is touch (at +35). Any critical resulting in the target catching on fire is ignored.
Fire Ball Can only affect one target and the range is touch.
Metal Fires Reduce all critical severities by two levels.
Stone Fires Reduce all critical severities by two levels.
Wall of Cold Forms an Ice Wall over the course of 10 rounds.
Ice Bolt Maximum range is half with a penalty of 25. If within 10 feet, no modification. Touch is at +35.
Cold Ball Maximum range is half with a penalty of 25. Area of effect is not affected. GMs should take liberal license with the critical results to determine how much if any surrounding water is frozen.
Call of Cold Forms an Ice Cube over the course of 10 rounds.
Water Wall No affect underwater, but can be spell mastered to slow ships on the surface.
Water Bolt Maximum range of 50 feet. Normal range penalties.
Command Current Can be used to create underwater currents to benefit swimmers.
Part Water Can be spell mastered to form various sized corridors of air within water. If this spell is used to cross a river, be sure to account for the damning of water on one side and the drying out on the other.
Slumber Mist This spell can be devastating to artificial underwater environments where oxygen is in short supply (i.e. dive bells, bubble cities, whatever).
Stun Cloud This spell is summoned from the elemental plane and therefore it will materialize as charged bubbles in the water. It will rise to the surface at 30 ft per round.
Vacuum This doesnt work in water, but it has severe repercussions on underwater environments. Vacuum essentially teleports the air out of an area, which is bad, bad, bad in your submarine, underwater cavern, air bubble, or whatnot.
Underwater Move. This spell allows a character to move with virtually no resistance, but does not compensate for leverage and buoyancy factors. Movement will be at normal rates. The caster uses the minimum combat penalty for the casters weapon type.
Unwater This spell disintegrates the water in the area of effect. With no air to fill that void, it creates a vacuum that is suddenly filled with water. Treat as a Vacuum attack of the same type (i.e. Unwater I is like Vacuum I, but with a much greater area of effect).
Dehydrate Fails underwater.
Desiccation Target gets hefty RR bonus underwater
Dehumidify Takes twice as long to lower the humidity and it returns at twice the rate.
Deoxygination Same as Slumber Mist, but worse.
Implosion Damn. There goes Gungan City.
Solid Destruction Almost every spell on this list could seriously impair the function of an underwater structure or vehicle. GMs beware. Quake can destroy coastal cities or small countries.
Entity Summons GMs will have to decide how helpful an air or water elemental can be in this environment.