Akaroa Harbour is home to a resident population of Hector's dolphins — the world's smallest oceanic dolphin and one of the rarest. Several operators run swim-with-dolphins trips from the Akaroa wharf throughout the day during summer (October to May). Participants swim in wetsuits provided by the operator; the water is cold but the experience is extraordinary.
The trips take about three hours and go out into the harbour, where the dolphins tend to congregate. There is no guarantee — these are wild animals — but sightings on most trips are reliable. Outside of swimming, dolphin-watching cruises from the wharf cover more of the harbour and are a good option for those who prefer to stay dry. Book in advance during the summer season.