Lyttelton Harbour / Whakaraupō is a major inlet on the northwest side of Banks Peninsula, on the coast of Canterbury, New Zealand; the other major inlet is Akaroa Harbour, which enters from the southern side of the peninsula. Lyttelton Harbour / Whakaraupō enters from the northern coast of the peninsula, heading in a predominantly westerly direction for approximately 15 km (9.3 mi) from its mouth to the aptly-named Head of the Bay near Teddington. The harbour sits in an eroded caldera of the ancient Banks Peninsula Volcano, the steep sides of which form the Port Hills on its northern shore.
The harbour's main population centre is Lyttelton, which serves the main port to the nearby city of Christchurch, linked with Christchurch by the single-track Lyttelton rail tunnel (opened 1867), a two lane road tunnel (opened 1964) and two roads over the Port Hills. Diamond Harbour lies to the south and the Māori village of Te Rāpaki-o-Te Rakiwhakaputa to the west. At the head of the harbour is the settlement of Governors Bay. The reserve of Otamahua / Quail Island is near the harbour head and Ripapa Island is just off its south shore at the entrance to Purau Bay.