Gas Please! –
A gas line running underwater just below the surface. You'll need an ignition as well (I assume this is automated and triggered). The ignitor is another gas line with permanent flame above water in line with the gas line underwater. When triggered, the gas line underwater becomes active and gas rises out of the water, the flame igniting the gas and giving you your "fire on the water" effect.
Travis "Big T" Russell
Big T Productions Inc
Owner and Operator of "The Plague" and "Camp Nightmare"
Customer Quote of the year: "Damn, I pissed myself"