During a nine-day visit, we investigated the algal ecology of Rangiwhakaea Bay, Great Barrier Island, northeastern New Zealand. Four subtidal algal zones were recognised, and these were mapped along with gravel and sand areas. The four algal zones were dominated by Carpophyllum angustijolium, coralline turf and paint, Ecklonia radiata, and Hummbrella hydra respectively. Carpophyllum angustijolium extended up into the low intertidal, its vertical width varying with the degree of wave exposure. Five other intertidal algal zones were observed. They were dominated by Xiphophora chondrophylla, Splachnidium rugosum and Catenellopsis oligarthra, Pachymenia lusoria, Hormosira banksii, and Cigartina alveata. Sixty-six species of algae were recorded from the region.