The "water twister" appeared at around 12:45pm out in the middle of the sea several nautical miles off Patong Beach, and remained in sight from the coast for about five minues, with several boats nearby, before finally dissipating.
The height was reported to be as high as 600 metres, while the diameter was estimated to be as much as 10 meters, spinning anywhere from 20-80 meters per second, and wind speeds of between 100-190 kilometres per hour, but as fast as 225 kph, capable of capsizing small boats.
Although tourists and boaters were alarmed and immediately fled from the direction of the waterspout, no reports of injuries or damages have yet been reported.
According to worldmeteorology.com, no heavy rains are expected in Phuket for the rest of the day, and through to tomorrow morning; however, some light rain is forecast for the southern part of the island tomorrow afternoon.
The US National Oceanic and Atmospheric Administration explains that waterspouts are essentially the same as tornados, but over water.
"Waterspouts fall into two categories: fair weather waterspouts and tornadic waterspouts.
"Tornadic waterspouts are tornadoes that form over water, or move from land to water. They have the same characteristics as a land tornado. They are associated with severe thunderstorms, and are often accompanied by high winds and seas, large hail, and frequent dangerous lightning.
"Fair weather waterspouts usually form along the dark flat base of a line of developing cumulus clouds. This type of waterspout is generally not associated with thunderstorms. While tornadic waterspouts develop downward in a thunderstorm, a fair weather waterspout develops on the surface of the water and works its way upward.
"By the time the funnel is visible, a fair weather waterspout is near maturity. Fair weather waterspouts form in light wind conditions so they normally move very little."
It advises that boats anywhere near a waterspout, in order to get to a safe distance, should move in a direction at 90 degrees to the apparent direction of the waterspout's travel.
Additional reporting by Eakkapop Thongtub