Hector's dolphin rarely exceeds 1.5 metres from snout to tail, which makes it the smallest marine dolphin on earth and one found nowhere outside New Zealand's coastal waters. Several hundred hold station inside Akaroa Harbour and along the Banks Peninsula shoreline through the year. Their presence is the reason Akaroa Dolphin Tour from Christchurch tours function as a fixed feature of the Canterbury calendar rather than a seasonal novelty. The harbour did not fill with dolphins by accident. It offers shelter, shallow water and a silt-fed food column that suits a small, coastal-bound species. The harbour itself is a ruin. Banks Peninsula was built by two overlapping shield volcanoes that fell silent roughly eight million years ago; the sea later flooded the collapsed craters, and Akaroa Harbour is what remains — a drowned caldera some 16 kilometres long, walled by lava cliffs rising several hundred metres from the water. Gravel carried down by the Waimakariri eventually welded the whole formation to the Canterbury Plains, turning an island into a peninsula. Volcanic dykes still stripe the outer headlands. Basalt columns, sea caves and blowholes punctuate the coast near Cathedral Cave and Timutimu Head, and white-flippered penguins nest in the scree beneath them. Protection came late but decisively. In 1988 New Zealand established the Banks Peninsula Marine Mammal Sanctuary, the country's first, drawing a boundary around roughly 1,140 square kilometres of coastal water and restricting the set nets that had been killing dolphins faster than the population could recover. The sanctuary was extended in 2008. These waters remain the reference site for Hector's dolphin research, and every licensed vessel works under Department of Conservation permit conditions governing approach distance, engine speed and the time any one pod may be held company. The village on the western shore supplies the other half of the appeal. A French expedition landed in August 1840, weeks after British sovereignty had been declared, and the street names — Rue Lavaud, Rue Jolie, Rue Balguerie — survive from that brief colonial misfire, which is why so many Akaroa Dolphin Tour from Christchurch tour itineraries are sold as paired harbour-and-village days. Onawe Peninsula, the basalt spit at the head of the inlet, carries the earthworks of a Ngāi Tahu pā and stays in view for much of the crossing. The road in from the city runs some 75 kilometres over the Hilltop saddle. At the far end, the waterfront office at 61 Beach Road, Akaroa 7520 keeps 08:30–17:00 hours seven days a week, and the counter there is the point where a long drive becomes a short voyage.