A Belgian tourist drowned in a river after the rubber dinghy he was riding capsized while he was rafting with friends in Thailand.

Nicolas Hinckxt, 30, was discovered floating lifeless in the water near the Mae Taman Elephant Camp in Chiang Mai province on Sunday, July 24.

Officers found his body trapped between two large rocks in the river after a frantic weekend-long search that was hampered by stormy weather.

The foreigner and three of his friends had gone whitewater rafting in the Taeng River on July 22 afternoon when their inflatable boat slammed into boulders in a rough part of the stream. The impact had sent Nicolas overboard into the rapids as the water dragged him under.

Their tour guide Panya Noibutr, 30, said he threw a lifeline towards the struggling holidaymaker, who failed to grab it and was swept away by the powerful currents.

Nicolas's damaged helmet and life vest were later found about two kilometres away from the scene.

His disappearance sparked an intense search, with local officials, villagers, and even his distraught Thai mother, who had reportedly flown in from Belgium, joining to scour the river.

Their efforts were disrupted by torrential rains, but operations finally concluded on Sunday after Nicolas's body was found jammed between two rocks along the stretch of river where his safety gear was found.

The Belgian national reportedly lived and worked in Belgium, and had visited Thailand for a holiday when the tragic incident struck. His body has been sent to a hospital for an autopsy, and will later be turned over to his family.

The Royal Thai Police said they will be investigating his death further.