Pelorus Sound (Māori: Te Hoiere; officially 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 55 kilometres (34 mi), between steeply sloped wooded hills, until it reaches its head close to the Havelock township. Pelorus has several major arms, notably Tennyson Inlet, Tawhitinui Reach, Kenepuru Sound and the Crail/Clova/Beatrix Bay complex. Its shoreline runs for 380 kilometres (240 mi).