The boat, the Elusive, was on the Piscataqua River heading for a marina at New Castle around 4pm on Saturday when a passenger noticed black smoke under the deck, the New Hampshire Department of Safety said in a statement. The New Hampshire State Coast Guard and Marine Patrol posted photos of the flames and thick black smoke billowing from the boat. Three passengers, as well as two dogs, jumped into the sea as the boat was engulfed in flames. They were rescued by other boats. The passengers, identified as Arthur Watson, 67, and Diane Watson, 57, both from New Canaan, Connecticut, and Jarrod Thumbs, 33, of Jupiter Florida, were taken to hospital and treated. and were released. Despite efforts to save the yacht, it sank in Maine and sank about two hours after the initial 911 call, authorities said. The causes of the fire are being investigated.