A family were seen on board a £6million superyacht shortly before it exploded into a fireball.
The 85ft craft caught alight and drifted from its moorings on Saturday at a marina in Torquay, Devon, triggering the closure of several local businesses and warnings to locals.
Despite the best efforts of fire crews the luxury yacht, called the Rendezvous, sank three hours later at around 4pm.
It comes amid speculation the close proximity of the vessel's electric nameplate to its on-board fuel store, which carries up to 8,400 litres, may have been the cause of the disastrous blaze.
Referring to the yacht's owner, a source told The Sun : "He recently had a back-lit electric nameplate put on which is near the fuel store."
A boat owner at the marina also said: "His yacht’s been at Torquay for about three years and was only recently re-wired. That may be a factor in the fire."
It is unclear who owns the yacht, which was last sold in 2022 and listed as the 7862nd largest in the world.
One local photographer claimed he often saw a family aboard the vessel on Sunday afternoons, and that they apparently left 35 minutes before the blaze.
He wrote on social media: "I’ve seen the family on it many weekends on a Sunday afternoon but apparently they were on it yesterday and left it about 35 minutes before it went up in smoke."
The Environment Agency feared the fire could spark a mini-ecological disaster because it had nearly a full tank of fuel aboard which is thought to have leaked into the sea.
A spokesman for Devon and Cornwall Police said at the time: "The boat is believed to have caught alight and broke away from the mooring but was later secured by the Fire Service near the pier. There have been no reported injuries.
"Shortly before 4pm the vessel became fully submerged underwater. The Harbourmaster supported by the Environmental Agency will look to safely recover the vessel in due course.
"All road closures and majority of cordons have now been lifted and the public are able to access the area again. One cordon remains in place at the pier.
"Enquiries remain ongoing to establish the cause of the fire, which is currently being treated as unexplained."
The Environment Agency said around nine tonnes of diesel may have been spilled into the ocean as a result of the incident and officials are working to limit the pollution.
It tweeted: "With yacht now sunk, and with approx 9 tonnes of diesel on board, focus now on pollution. Pollution response led by harbour master.
''Our officers are helping with advice and guidance on bathing water quality etc.
"Our officers have been checking air quality around Torquay harbour this afternoon following the yacht fire, which was declared a major incident.
"Thought to be no real issues with air quality, but we're keeping an eye on the situation."
An eyewitness to the blaze said things had escalated over the course of the afternoon.
"85ft yacht in fire. A few hours ago," they tweeted, along with a long shot of the boat harboured by the pier, taken from a nearby shoreline.
"Things have slightly escalated since this," they continued. "Whole front of Torquay now closed, including all businesses."
According to roads traffic and monitoring service, Inrix, the incident had caused traffic blocks in both directions along Torbay Road.
