This is the spectacular moment a thin waterspout tornado formed next to a curtain of rain at sea in the Philippines.

The vortex spun off the coast of Merida town in Leyte province on July 12, frightening fishermen who were trawling for tuna in the area.

As the twister continued rotating, a burst of rain fell from storm clouds next to it.

Waterspout tornadoes form when wind merges from opposite directions near the water's surface, creating a small area of spin. Warm air at the surface causes the spinning air to rotate faster and start to rise – picking up water simultaneously and forming the distinctive elephant-funnel shape.

As warm air rises, the cooler air moves in below and then rises, too. Sometimes the air spins so fast that it stretches and a funnel appears from the water to the thunderstorm cloud above.

Waterspouts are generally not dangerous but they can be a risk for aircraft flying through the area and for coral reefs and marine life in the water immediately below. Sailors should also try to avoid waterspouts as the power of the wind can cause damage.