Samrit Pimol, 59, a local resident of Thepkrasattri in Thalang, called in the discovery on the 191 police hotline at about 3pm.
Mr Samrit described the body as that of a fair-skinned woman wearing a red swimming costume. He believed the body to be that of a foreign tourist.
However, running out of fuel and unable to stay alongside the body any longer, Mr Samrit came back ashore at at about 5:30pm with a photo of the body to show police and rescue workers.
A combined search by a host of local organisations and rescue workers failed to locate the body, prompting the Royal Thai Navy to launch their own search by boat and helicopter.
That search was called off at 7pm last night due to the failing light.
The body is believed to be that of 27-year-old Chinese tourist Yang Juan, who disappeared while swimming with friends in dangerous surf at Na Toei Beach in Thai Muang, Phang Nga, last Saturday (Feb 24).
Ms Yang was on her honeymoon. (See story here.)
Tour guide Anuwat Kangsadanbanpot, 26, said he had warned the group to not enter the water at the beach as it was too dangerous to swim and posed a danger to their lives. (See story here.)