Investigations are underway into what led a tourist boat to run aground just inside the Akaroa Heads

The Black Cat Cruise vessel was carrying 41 people when it ran into trouble on Saturday - all were safely rescued.

The boat will now be submerged to prevent further structural damage from wind and sea conditions, before it's lifted out.

Louise Cook - the Chief Accidents Inspector from the Transport Accident Investigation Commission - says it's a systemic inquiry, that doesn't apportion blame.

She says they're gathering all the evidence on factors like driver fatigue, vessel maintenance, and how it was being navigated.