6/17/2011--Seattle, WA. USA..Houseboats on Lake Union in Seattle. Seattle, Washington is home to a relatively large collection of floating houseboat neighborhoods, particularly in Lake Union and Portage Bay. The earliest houseboats in Seattle were recorded in 1905, and peaked with over 2000 houseboats in the 1930s. There are currently approximately 500 houseboats in Seattle. ..©2011 Stuart Isett. All rights reserved.