Though a powerful magic user, many of her spells are limited in that sound and water are two of their major components in casting. Sound, in that they are cast verbally, specifically via singing. As sound travels differently in air than in water it has forced her to adjust her spells accordingly. Water, well, that ought to be self explanatory.
Hydromancy
Animate Water
Turns a small quantity of water into a small water elemental; cast only under water.

Breathe Air/water
Spell allows target to breathe under conditions target would normally suffocate in, can be cast above or below water.

Create Water
This creates water in either in a container or over a specified span of area, as in a gentle rainfall. Rather simple spell, she is now able to cast above or below water.

Control Water
Spell raises or lowers the water level of a specified area; able to cast above and below water.

Control Tide
A complex spell involving the changing of the tides. Seldom used as it affects more than just the area it is cast upon; only able to cast below water.

Drown
When target or targets are submerged in water, find it difficult to surface or tread water; cast only under water.

Dispel Magic
Ends the affects of a specified spell either on an object or indicated area. Olitia’s roll must match that of the roll spell was cast on (if known); can be cast above and below water.

Endure Elements
The target is protected for an indicated amount of time from a specific energy type; cold/water, air, fire, electricity, acid, or sonic. This absorbs damage only and does not reduce other side affects such as drowning; can be cast above or below water.

Fog
This conjures a cloud bank of obscuring mists, able to cast above and below water.

Solid Fog
As in the spell above, but the fog slows movement of any caught within it; able to cast above and below water.

Stinking Cloud
As in Fog, creates a bank of fog, but in this the fog is also disorienting and nauseating; able to cast above and below water.

Acid Cloud
As in Solid Fog, creates an obscuring mist that slows movement, but the mists are now acidic causing a few minutes of burning. This can be cast only below water.

Maelstrom
Creates a violent, powerful whirlpool, at sea; an extremely difficult spell can be cast only under water.

Tempest
This conjures a powerful storm at sea, with heavy rain, tidal waves, and so on. A very complicated spell; can be cast only below water.
Siren Spells
Charm Person/Animal
Through an enchanting song, charms a target animal, humanoid, or small group into trusting and befriending caster. Target will not obey commands to hurt themselves. Above water, can only be cast upon single target.

Charm Monster/Magical creature
Like spell above.

Invigorating Chant
This song increases adrenalin and aggressive tendencies of target or targets; Can be cast above and below water

Soothing Song
A gentle melody that soothes listeners and eases aggression can be cast above and below water.

Shout
An earsplitting scream that temporarily deafens targets; cast above and below water.

Wail
A heartrending cry that summons feelings of hindering depression and sadness; cast above and below water.