It's a boat! It's a taxi. It goes downtown!
The West Seattle Water Taxi is a passenger ferry that operates between Seacrest Dock in West Seattle and Pier 50 in downtown Seattle. From October through April it runs weekdays only, and only during morning and afternoon peak commute times. There rest of the year it runs daily, with evening runs on Fridays, Saturdays, and during most nighttime sports events. Check the Website for schedules.
Pay as you board, with an ORCA card, Metro ticket, or cash. Ticket dispensing machines at both docks can take credit or debit cards. There is no extra charge for bicycles.
On the West Seattle side, there are shuttles from Seacrest dock to both Alki Beach (Bus 775) and the main West Seattle business district, the Alaska Junction (Bus 773). In the summer, the shuttles do not run during the boat's extended evening hours. Again, check the Website for schedules.
Regular downtown commuters gravitate to the water taxi because it is comparatively immune to the typical Seattle traffic tie-ups caused by rain, sun, snow, fog, black ice, sports events, parades, or the sudden appearance of a large glacier-topped mountain to the southeast.