Couple people have asked about this via email. My reply:
It’s long been an anchorage – the Coast Guard administers – usually ships waiting to call at Seattle or Tacoma.
Some context in this 2016 story
Of the two there now, Triumph recently called in Tacoma, and is due next in Vancouver. Morning Cloud is due to dock in Seattle – it’s a bulk carrier so could be headed for the grain terminal (which is busy with another ship right now) or possibly the Duwamish (less likely).