Staff at Kata Beach Resort noticed the dolphin in trouble.
At this time of the year, with strengthening monsoon waves and increased surf on Phuket's beaches, sick young dolphins can struggle to survive.
Locals at Kata beach attempted to steer the dolphin from the strong surf at the southern end to a calmer spot, where one rescuer was able to scoop the creature up into his arms.
Marine biologists gave the dolphin a calming injection to prevent shock, and transported it to the Phuket Marine Biology Centre, on Phuket's eastern Cape Panwa.
Marine biologist Patcharaporn Kaewmong said the dolphin was a two-year-old female, about 1.2 metres long and weighing 20 kilos.
Test later today should establish what is causing the dolphin's problems and whether it can be treated and returned to its pod companions.