Hydro-Thermokinesis

Hydro-Thermokinesis is the power to heat and boil water. The only mermaid to have this power is Jenny.

The hand movement for this power is a fist; this may symbolize the amount of heat needed to boil water. This power is very useful when she need to dry her tail. With this power, she can increase body temperatures and dehydrate others around her.

If Jenny's power was enhanced, it is likely that she would have gained Pyrokinesis and/or Electrokinesis: the abilities to control fire and lightning. However, the series ended before it was confirmed.

Trivia

 * This is the most dangerous of the water powers, and may cause the most damage.