Welcome to Tiny Homes, an idea that is more popular with minimalists than with neighborhood associations and zoning boards. We'll point out the fun parts. You'll have to check out the logistics and legalities - like, what keeps it afloat.
Tiny houses enable tiny living, fewer things to tend and fix. Put the tiny house on floats and remove the need for gardening and landscaping. Tiny houseboats aren't new to Seattle. This one was built in 1930. For $229,000 you get a very open studio floor plan with one bath and 500 square feet, and nautical access to Portage Bay, a quick row to UW or Lake Union.
It's more classic than old. Dark shingled siding with a bit of a pitched roof. Doors and windows that look updated. It isn't trying to be something fancy, but it isn't dull. This is what a tiny houseboat should look like. The end wall opens with double French doors that turn in the lake into an expansion of your personal space.
Inside it is wood paneling for the walls and ceiling. It is also as studio, so the only private place indoors is probably the bathroom. The open layout also means the views aren't blocked by interior walls. A fireplace provides ambience to a house that already has more than usual simply because of what it is.
Outside, the deck wraps around the house providing seating, boat storage, and maybe even moorage. If you've got water toys, they can be more convenient than a car in a garage. Sit on the deck and watch the traffic go by. Boats cruising by on the water are far more entertaining than cars cruising by on a street.