The Aratere ferry was undergoing a freight only voyage when it suffered a steering failure causing it to run aground shortly after leaving port at 9.45 last night.
Interislander general manager Duncan Roy says there are no injuries and the vessel's watertight.
Nelson MP Rachel Boyack says she's had contact with the crew on board during the night and everyone's fine.
The Picton Harbour Master was taken onboard the ship last night and it will be refloated as tidal conditions allow.
The next high tide in Picton is at nine this morning.
Maritime New Zealand is investigating the cause of the grounding.
It's the latest in a series of troubles for Kiwirail, the same boat lost power in the Cook Strait last year and the Interislander's Kaitaki had a similar issue too.