Dressed in just a pair of black and green/yellow swim shorts, the man appeared to have head wounds and a wound on his stomach. Investigators could not be certain whether the wounds had been inflicted before or after death.
He was about 180 centimetres tall, according to police, with a distinctive tattoo on his left calf that appeared to be circular razor wire, with a central swastika.
Phuket Marine Biological Centre researcher Chaimongkul Yamarunpattana quickly alerted authorities when he found the floating body about 9am.
Police reckoned the man could have been in the water for between a week and 10 days.
In September, a body was found at Surin beach that initially appeared to be a female, with wrists bound. However, forensic pathologists established that the body was male, and that the wrist bindings were entrails.
It hasn't yet been determined whether that body was Caucasian or Asian.
Officers from Karon Police Station are checking with other stations on Phuket to see whether any Caucasian man fitting the description has been reported missing.
The body found off Kata Noi today was taken to Vachira Phuket Hospital.