Transport Accident investigators say the cruise ship that ran aground in Fiordland on Wednesday night was previously subject to an investigation.

The Fiordland Navigator became stranded on rocks in Doubtful Sound shortly after 6pm.

All 67 passengers and crew onboard were evacuated, with one person sustaining minor injuries.

The boat's hull was breached and it took on water, but it was refloated later that night and returned to its berth at Deep Cove.

The Transport Accident Investigation Commission is now investigating, talking to witnesses and collecting evidence from the site.

Chief investigator Naveen Kozhuppakalam told Morning Report the ship was investigated back in 2006.

However, he said it was too early to draw any possible links to the latest incident.

Kozhuppakalam said groundings were considered serious incidents because they could damage the hull and create a loss of structural integrity of a vessel, which could potentially result in sinking or capsizing.

"The commission's investigation should draw into any particular lines of inquiry that [the grounding] has been a systemic issue that we might identify, but at this stage it's too early to comment on any of that.

"At this stage ... the circumstances are quite scanty... What we do know though is that the evacuation was quite successful.

"Once the vessel grounded, the crew responded well and the passengers were safely evacuated, so there was a good outcome."

It could be up to two years before the marine safety inquiry was completed.

Southland District Council mayor Rob Scott told Morning Report the area saw a large number of visitors at this time of year.

"When you look at Fiordland we get hundreds of thousands of people going through there ... It normally is trouble-free, but every now and then these things do happen and the investigation will reveal what happened there."

The boat's operator, RealNZ, is also investigating the incident.

Main image: The Fiordland Navigator, which became stranded on rocks in Doubtful Sound shortly after 6pm on Wednesday, January 24.