Hydro-Thermokinesis is the power to heat and boil water. One can also create fires when using this ability. The hand movement for this power is a closed/closing fist. This may symbolize pressure, tension, and the amount of heat needed to boil water. This is the most dangerous ability of the three original powers (hydrokinesis, hydro-cryokinesis, hydro-thermokinesis). This power can make someone sweat uncontrollably. When enhanced, it can be upgraded to Pyrokinesis and Electrokinesis. This power belongs to Rikki Chadwick in H2O: Just Add Water and every mermaid in Mako Mermaids.