Darcy sent in this tip:
Rumor has it that they are shooting scenes from [the New Lynn Shelton film starring "Laggies" Keira Knightley] on the Skansonia [tonight, Thursday] after 10pm, possibly setting up shop in the marina nearby.
The Skansonia is a decommissioned ferry docked on the Wallingford shores of Lake Union. From the Seattle Film Guide post:
Anonymous Content is in pre-production on the upcoming major indie feature film “Laggies” starring Chloe Moretz, Sam Rockewell, and Keira Knightley. Filming will take place in Seattle, WA beginning June 3, 2013. Seattle native Lynn Shelton will direct from a screenplay by Andrea Seigel.
IMDB describes the plot “A woman stuck in permanent adolescence lies to her fiancé about going on a retreat and spends the time hanging out with friends instead.”