The Bay of Islands is one of the most reliable places in New Zealand to see wild dolphins. Bottlenose dolphins — some of the largest individuals of the species anywhere — are resident in the bay and frequently encountered. Common dolphins also visit, often in much larger groups. Dolphins regularly approach boats and ride the bow wave.
Most tour operators offer dolphin-watching as part of their island cruises; dedicated dolphin-swimming tours operate separately, with passengers able to enter the water when dolphins are close enough. Swimming with wild dolphins requires careful management to avoid disturbing the animals — reputable operators follow Department of Conservation guidelines. A basic cruise from Paihia Wharf takes 2–3 hours; the Hole in the Rock tour often incorporates dolphin encounters en route.