Hypothetical:
An aether kineticist on land is using tk blast to attack an enemy submerged in water.
Since it's a big ball of energy would it detonate on impact with the surface of the water or does it count as a normal enough ranged attack that takes the penalties listed in the aquatic terrain section?
There is also the following, about submerged creatures and attackers on land.
A completely submerged creature has total cover against opponents on land unless those opponents have freedom of movement effects.
With total cover, the kineticist wouldn't be able to attack it.