Clipper Vacations spokeswoman Janis Smith said the 159 passengers aboard a 113-foot Victoria Clipper catamaran got off the ship at Shilshole Marina. She confirmed no one was injured.
Smith says the ship was returning from a daylong excursion to Washington's San Juan islands when a fire was reported in some insulation surrounding one of the turbine engines.
The spokeswoman says the crew sealed that compartment and deployed a chemical fire suppression system, then diverted to the nearby marina.
Seattle Fire spokesman Kyle Moore said firefighters were making sure the fire was out.
The fire was reported about 7:20 p.m. when the boat was off Edmonds, north of Seattle.
A woman aboard the clipper said fellow passengers and crew members remained calm throughout the ordeal.
"The captain just said, 'There's been a small fire, no problem.' They had to flood the engine room with a fire retardant and they had it all under control, it was great," the passenger said.
Smith said the company dispatched buses to bring the passengers back to the Seattle waterfront, where their trip began.
Traffic was delayed near pier 55 as passengers left the ship.