Akaroa Harbour is part of Banks Peninsula in the Canterbury Region of New Zealand. It enters from the southern coast of the peninsula, heading in a predominantly northerly direction. The name Akaroa is Kāi Tahu Māori for "Long Harbour". Ōnawe Peninsula is at the head of the harbour, the former site of a Māori pā. The entire harbour is the caldera of an extinct volcano.

The towns or settlements of Akaroa, Duvauchelle, Barrys Bay, French Farm and Wainui lie on the shoreline of the harbour. Cruise ships occasionally enter the harbour, with the passengers visiting Akaroa.

The 475-hectare (1,170-acre) Akaroa Marine Reserve was given approval in 2013 after a 17-year campaign to get it established.

As of 2011, of the seven sites that are sampled in the harbour for water quality, six are graded as "good" and one as "fair" in terms of recreational use. Rainfall affects the grading.