Allan Stanley, 76, suffered fatal injuries when he was hit by the boat’s propeller at Hondoq ir-Rummien Bay in Qala, Gozo. The boat was driven by a 19-year-old local man, who took Mr Stanley to the shore where he was given first aid by lifeguards.
Maltese police confirmed that Mr Stanley died in the ambulance en route to Gozo General Hospital.
The grandfather from Nefyn, North Wales, was two months into his Malta holiday with his wife, Diane, at the time of the incident.
The retired businessman and father of four regularly visited Malta, where he would swim two miles a day in the picturesque waters of the bay at Hondoq ir-Rummien.
Mr Stanley’s son, Russell, 43, said: "He was hit by a boat and they tried to repair him in the ambulance.
"He was a keen swimmer and kept very fit for his age. He'd swim a mile or two every day when he was over there.
"Dad was a hard worker but had reached the age where he deserved a bit of time abroad.
"He loved it there, he always looked forward to going."
Police investigations are ongoing. An inquiry into the death has been launched in Malta by duty magistrate, Paul Coppini. The 19-year-old Maltese man who was driving the speedboat is being questioned about the accident.