A plea for people to be very conscious of the dangers of going out on the water

A search is set to resume this morning on Auckland's Manukau Harbour, for one of two people missing since Tuesday, after their boat sank near Puketutu Island.

Emergency crews have been sweeping the waters surrounding the island, with a Police Eagle helicopter scouring the wider area.

Manuwera-Papakura councillor Daniel Newman says people need to wear lifejackets, bring emergency response equipment, and be aware of how treacherous conditions can get.