Crews responded to the scene, the North Lake Marina in Kenmore on NE 175th Street, at around 11 p.m. after receiving reports of a possible fire.
Light smoke was coming from the boat when first responders arrived, then flames erupted.
Officials say it took about 45 minutes to extinguish the fire
One person was aboard the vessel when the blaze broke out. That person was able to get off safely and there were no injuries reported.
Authorities say teams are now watching to make sure runoff from the firefight does not contaminate the water at the marina.