bove the west end of Big Manly Beach sits the Headland Pā — one of Ngāti Kahu's five settlements along the Peninsula. Its commanding views of the coastline in three directions made it an ideal lookout against approaching enemies.

Following the Mahurangi Crown Purchase in 1854, the Polkinghorne family were among the first European settlers, arriving in 1877. The bay took their name until the 1920s, when developers Laurie Taylor and Bill Brown began subdividing the land and borrowed the name "Manly" from the Sydney bay. After an objection from a Polkinghorne family member in the 1970s, Polkinghorne Bay was retained as the official name for the broader Waiau area — though most locals simply call it Big Manly.

Waiau encompasses the three bays of Swann Beach, Big Manly and Tindalls, with Big Manly and Little Manly (on opposite sides of the Peninsula) becoming popular visitor destinations from the 1920s.

William Polkinghorne the younger, born in 1859, remained in the area after his parents' passing and in 1916 built a Post Office store and cheese factory on the hill between Manly and Arkles. The cheese factory closed after just two years. Ken and Edith Hopper took over the store in 1927.