Work is underway to recover a tourist boat stranded just outside the Akaroa Heads - which has leaked marine diesel fuel into the sea

The Black Cat Cruise vessel ran aground on Saturday, with 38 passengers and three crew on board - none reported any injuries.

Environment Canterbury says the boat will be moved to deeper water and submerged, before being removed.

Meanwhile, the Transport Accident Investigation Commission has opened an inquiry.

Chief Investigator of Accidents, Louise Cook says investigators have arrived on scene.

She says their focus is on collecting perishable evidence, such as people's memories, and electronic data.