Pelorus Sound / Te Hoiere is the largest of the sounds which make up the Marlborough Sounds at the north of the South Island, New Zealand. The Marlborough Sounds is a system of drowned river valleys, which were formed after the last ice age around 10,000 years ago. Pelorus Sound has a main channel which winds south from Cook Strait for about , between steeply sloped wooded hills, until it reached its head close to Havelock town. Pelorus has several major arms, notably Tennyson Inlet, Tawhitinui Reach, Kenepuru Sound and the Crail/Clova/Beatrix Bay complex. Its shoreline runs for .