The ferry left Wellington shortly after 8am and arrived in Picton just before midday.
Passenger Nick Simcock said those onboard had been told the ramp was stuck and staff had been working for the last 2.5 hours to free it.
"We boarded in Wellington about 8am and it was a great sailing across the channel but we arrived about midday and no-one has been able to get on or off the ferry, the back door ramp is firmly stuck," Simcock said.
"It's something to do with the mechanism, the pins are stuck that lock the door into position."
Simcock is heading to the Marlborough Sounds for a fishing and diving trip with friends and he said they were keen to get off the ferry so they could get on with that.
"Everyone is resigned to the fact I think, we have been down this road before with the ferries here."
Bluebridge has been approached for comment.
