Normal service is resuming after an illness outbreak forced NorthLink to take one of its ferries off the Aberdeen to Shetland route.
The Hjaltland was withdrawn from service earlier this week for 48 hours after a bus tour party was affected.
The company's sister vessel Hrossey was instead running a continuous shuttle service.
NorthLink said normal service was expected to resume on Thursday.
The company apologised for any inconvenience that had been caused.