The dead body of a missing German tourist was found this afternoon floating off the coast of Thailand's notorious Death Island.

Horrified passengers on a passing diving boat noticed the corpse of Florian Storz, 35, face down in waters off Koh Tao in Surat Thani province on February 6.

He was wearing the same pair of black shorts he was last seen in while riding a rented motorcycle before he went missing on January 31.

Colonel Panya Niratimanon from the neighbouring Koh Phangan island police station said the body found today matched CCTV images of Florian and medics had confirmed the identity.

He added: 'The body of the missing tourist was found today. The captain of a boat that was taking tourists to learn diving noticed that a male body was floating in the area, wearing black shorts and without a shirt.

'After being notified, police and rescue teams went to the location. The corpse was a tall foreign man.

'The rescuers brought the body onto the boat for a preliminary inspection and compared it with the pictures of the missing man, who was also wearing black shorts before he went missing. There was also a matching tattoo.

'The body was sent to Koh Tao Hospital for doctors to verify the identity again and the director of Koh Tao Hospital, Dr. Artit Khamchan, examined the body and found it was Florian Storz.'

Florian was travelling with his girlfriend when the vessel left the island of Koh Phangan in Surat Thani province on January 31 evening.

The German national from Gengenbach mysteriously plunged overboard 15 minutes into the journey shortly after 6pm local time.

The ship, named Racha 8, immediately turned around to search for the missing holidaymaker. Police, marine officials, and rescue volunteers later divided into teams on February 2 to find the tourist.

Rescuers scanned the ship's route, coastal areas, and nearby islands but failed to turn up anything on his location. The search and rescue was also hampered by poor weather and visibility immediately following the incident.

Florian's girlfriend, who was not named by police, could not give a possible motive for her partner's sudden plunge into the sea.

She reportedly told officers they were enjoying their trip before the unexplained incident on the boat.

It is still unclear why he went overboard.

Police said that Florian had landed at the Suvarnabhumi International Airport in Bangkok on December 26. His visa was set to expire on February 2.

Koh Tao has been dubbed 'Death Island' following a number of unexplained deaths and unsolved suspected murders.

British backpackers Hannah Witheridge and David Miller were bludgeoned to death on the beach by the son of a local official before he fled and police helped to cover up the crime. Two Burmese migrant workers were framed and jailed for life.