Reotahi Bay is a shallow shore dive on the edge of the Whangarei Harbour Marine Reserve, where sand and seagrass lead into oyster-coated boulders and scattered moorings. The sheltered near-shore section is the easiest part to work, but the water around Motukaroro can tighten quickly as the tide runs. It suits calm-day snorkeling or a conservative scuba outing with a careful plan for entry, exit, and timing. Expect a local-bay feel with reef-edge fish life and plenty of small structure to explore.