A tragedy in Spain has highlighted a little-known danger that experts warn can turn a luxury hot tub into a death trap.Investigators are examining whether a powerful suction system played a role in the deaths of a holidaying couple found at a villa in Cullera, near Valencia.Thomasina Tobin, 51, and her husband Patrick Tobin, 48, were discovered by their teenage children after they failed to return from using the property's jacuzzi.Spanish authorities have not yet confirmed the exact cause of death and toxicology tests are ongoing.However, reports from Spain suggest investigators are exploring the possibility that one of the pair became trapped by the hot tub’s circulation system before the other attempted a rescue.This hazard, known as suction entrapment, occurs when a bather becomes pinned against a drain or outlet by the force of water being pulled into the pump system.The resulting vacuum can be so powerful that victims are unable to free themselves and, in some cases, even nearby adults have struggled to pull trapped people to safety.Post-mortem exams conducted on Ms Tobin, from Co Monaghan, Ireland, and Mr Tobin, originally from New Zealand, ruled out foul play, and no signs of forced entry or suspicious activity on nearby CCTV cameras were detected. Spanish police believe Thomasina Tobin died while attempting to save her husband after he became stuck underwater at a spa in a luxury villa in SpainMarks and scratches were reportedly found on both bodies as well as blood in the cloudy water of the hot tub, and a strong chemical smell was noted by police.Local newspapers said suction marks were found on the couple by authorities.However, they were allegedly more pronounced on Mr Tobin – leading investigators to believe he was pulled under the water first and his wife passed away attempting to recover him.‘According to initial investigations, the excessive suction force would have imprisoned the couple inside the bathtub, which triggered a situation of extreme anguish and desperate physical effort to free themselves from the hydraulic grip,’ Valencia newspaper Las Provincias said.‘The autopsy findings almost definitively reinforce the theory of accidental entrapment.‘Preliminary analyses indicate that the victims suffered cardiac arrest brought on by acute stress following physical exhaustion and the desperation of the moment.’Although rare, suction-entrapment incidents have caused deaths around the world.One of the best-known cases involved seven-year-old Virginia Graeme Baker, who died after becoming trapped by the drain in a spa in the United States. A room in the Colina del Sol complex in Valencia, where the couple were staying The force holding her underwater was reportedly so strong that adults trying to rescue her could not pull her free until the drain cover broke.Her death led to sweeping safety reforms and new requirements for anti-entrapment devices in pools and spas across America.However, similar requirements are not universally adopted and standards can vary significantly from country to country.Another case involves a 14-year-old boy whose intestines were sucked out by a swimming pool filter at a Spanish leisure centre.Meanwhile in 2021, a father issued a dire warning to fellow parents about hot tubs after his son was ‘sucked into a filter’ and left unconscious.Alex Williams, from Shrewsbury, Shropshire, said his young son Harry had been enjoying the tub when he was suddenly pulled beneath the water by a filter outlet.Thankfully his family witnessed the incident, but it took three men to release him and pull him to the surface.Given their difference in size and strength, suction entrapment is significantly more common in children than adults. The tragedy has highlighted a little-known danger that experts warn can turn a luxury hot tub into a death trap (stock image) In 2021, a father issued a dire warning to fellow parents about hot tubs after his son was ‘sucked into a filter’ and left unconscious Modern pools and spas can incorporate safety features designed to reduce the risk, including compliant drain covers, multiple suction outlets and systems designed to limit or release dangerous suction.Safety campaigners advise bathers never to sit on drains or use spas where covers appear damaged or missing.Despite the widespread speculation, one expert said he isn’t convinced suction entrapment was behind the recent deaths.Matt Reynolds, a forensic engineer and aquatic safety expert who investigates swimming pool and hot tub accidents, told the Daily Mail: ‘The fact pattern doesn’t fit with what you would typically see in an entrapment-type incident.’He explained that with body entrapment a seal is made – typically with the torso – over a suction outlet.‘These drains are typically located on the bottom of the hot tub or spa pool – most of which are 3.5-4ft in depth,’ he said. ‘Or they would be on the vertical face of the seating area, around the calf area.’Mr Reynolds said it would be unusual for someone to have their torso in these locations – especially an adult. However, he said reports of a strong odour of chemicals could be important. ‘You wonder whether there was a chemical exposure incident,’ he added.