A huge waterspout tornado stunned locals as it formed off Indonesia's coastline.

Footage shows the twister touching down at sea, emerging from a blanket of dark clouds over Tanah Bumbu Regency, South Kalimantan Province, on Monday, July 14.

An onlooker said: 'The whirlwind at Pagatan Beach, hopefully, won't reach residential areas.'

Two types of tornado form at sea - tornadic waterspouts and fair-weather waterspouts. Tornadic waterspouts form from thunderstorms, just like land tornadoes, while fair-weather waterspouts are typically smaller and less powerful without the need for storms.

Both types of waterspout tornadoes are created when there is a strong difference in air pressure between the surface of the water and the air above it. This difference in pressure creates an updraft, which draws air from the surface of the water into the atmosphere. As the air rises, it cools and condenses, forming a cloud. The cloud can then rotate, forming a waterspout.

It is rare for waterspouts to cause severe damage. However, in August 2023 two tourists were killed and six injured when a waterspout tornado hit their boat on an estuary river in Phetchaburi, southern Thailand.