A 12.5m yacht with a dog aboard sank in Cass Bay, near Lyttelton, during the wild weather overnight.
Environment Canterbury (ECan) said the yacht sank on its moorings. It said a blue heeler dog called Buddy was on board at the time but was saved and had been safely returned to its owner.
It said the yacht contained 1000 litres of diesel but there had been no significant loss of oil.
The debris was being cleared by ECan staff from today.
"If members of the public do find debris, please do not touch it, and instead call 0800 765 588 to report any sightings,” ECan said.
MetService said earlier the rain caused surface flooding on some southern slopes of Banks Peninsula but started to ease about 3.30am on Wednesday.
Wind gusts last ight reached over 100kmh in exposed places on the peninsula.
