Lyttelton Harbour / Whakaraupō is one of two major inlets in Banks Peninsula, on the coast of Canterbury, New Zealand; the other is Akaroa Harbour.
Approximately 15 kilometres (9.3 mi) in length from its mouth to Teddington, the harbour sits in the erosion caldera of the ancient Lyttelton 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 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 Rāpaki to the west. At the head of the harbour is the settlement of Governors Bay. The reserve of Quail Island is near the harbour head and Ripapa Island is just off its south shore at the entrance to Purau Bay.
The harbour provides access to a busy commercial port at Lyttelton which today includes a petroleum storage facility and a modern container and cargo terminal.
Hector's dolphins, a species endemic to New Zealand, and live in the harbour.
Māori referred to the harbour as Te Whakaraupō, with this translating as harbour of the raupō reed. The common original European name for the harbour was Port Cooper, after Daniel Cooper). A less common early name was Cook's Harbour, based on the early explorations by James Cook; the equivalent naming convention referred to Akaroa Harbour as Bank's Harbour after the botanist Joseph Banks. The surveyors under Joseph Thomas who surveyed Canterbury in the late 1840s named the harbour Port Victoria after the monarch of the United Kingdom, but the name did not find common acceptance. The name was officially changed to Lyttelton Harbour in 1858, in honour of George William Lyttelton, who was the chairman of the Canterbury Association. The official name of the harbour was amended again to become a dual name by the Ngāi Tahu Claims Settlement Act 1998.