Granted Powers: You are at one with the Plane of Water, able to navigate it and weaponize it at will.
A druid who has this domain can use her wild empathy to influence a creature with the water subtype if its Intelligence score is 1 or 2. Furthermore, she can choose to replace the 8th-level power with a Small elemental familiar that corresponds to her element, as if she possessed the Improved Familiar feat. Her effective wizard level for this ability is equal to her druid level and stacks with other classes that grant a familiar.
This grants you a bonus on Swim checks equal to 1/2 your druid level and allows you to breathe normally underwater. You can end the effect when delivering a touch spell to create a pseudopod of water that extends your effective reach by 5 feet for that attack. When used underwater, the pseudopod instead increases your reach by 10 feet. You can use this ability a number of times per day equal to 3 + your Wisdom modifier.
At 8th level, you can strike an area with a pressurized blast of water in a 5-foot-radius column 30 feet tall with a range of 60 feet. Creatures in the area take 1d6 bludgeoning damage per druid level and are knocked prone. When used underwater, the radius and height double, and the effect instead creates a powerful eddy that causes affected creatures to lose their Dexterity bonus to Armor Class for 1 round instead of knocking them prone.
A successful Reflex save halves the damage and prevents the secondary effect. You can use this ability once per day, plus an additional time for every 6 levels beyond 8th.
Domain Spells: 1st—touch of the sea, 2nd—elemental speech, 3rd—water breathing, 4th—planar adaptation, 5th—solid fog (functions underwater), 6th—mass planar adaptation, 7th—fluid form, 8th—seamantle, 9th—tsunami.
Pathfinder Campaign Setting: Planes of Power © 2016, Paizo Inc.; Authors: John Compton, Paris Crenshaw, Eleanor Ferron, Thurston Hillman, and Jessica Price.