The four members of the crew from the Delta Captain were plucked from their life raft Saturday afternoon, the Coast Guard said in a release posted on its website.
The Coast Guard said the four were taken to shore in Monterey to be checked out by medical personnel. No injuries were reported.
The Coast Guard said the sunken tug boat may still be attached via towline to a barge. Recovery efforts were under way.
The Coast Guard didn't say what caused the tugboat to go under.