The video clip, which has a length of about one minute, 50 seconds, was posted by Facebook user "Nai Lay Chao Lay Patong" (ในเล ชาวเล ป่าตอง) who claimed that the clip was taken on June 9, 2016, near Laem Phrom Thep cape, off the island's southwest coast.
"We were out on our longtail boat looking for fish, and along comes this whale shark, clearly not scared of us, and play swimming with us. We didn't do anything to it," the post reported.
A whale shark sighting off Phuket was last reported near Nai Yang Beach back in April, which followed another sighting off the island's east coast in October, last year.