Investigators said a small aluminum boat and a yacht collided approximately one mile off shore around 4:30 p.m., causing the smaller vessel carrying two passengers to overturn.
The crew aboard yacht, with the help of Suquamish police who happened to be nearby, pulled the two men out of the water. They began performing CPR on one of the men, who had apparently suffered sudden cardiac arrest and lost consciousness.
The man was pronounced dead minutes later.
The second victim, a man in his 70s, was alert and conscious. He was taken to an area hospital as a precaution once the yacht docked at Shilshole Bay Marina.
The Seattle-based yacht is named Shelmar. No other information about the vessel was immediately available.
A drug recognition expert evaluated the man who was driving the larger boat and didn't find any signs of impairment, according to police.
Police are still trying to determine what caused the crash.