Crooked Harbour or Kat O Hoi is a harbour at the northeast of New Territories, Hong Kong. The harbour is connected to Double Haven and the bigger sea of Mirs Bay. Crooked Island, also known as Kat O, and several islands, including Ap Chau, form the harbour with the mainland New Territories.

Islands

Islands of Crooked Harbour include:

Ecology

Wave-cut "benches" of 6 to 10 meters wide form along the sediment layers at Crooked Harbor and Ping Chau, which are uncommon elsewhere in Hong Kong's coastline. Eelgrasses discovered at Lai Chi Wo in 1977 were granted protection by the Agricultural and Fisheries Department of the Hong Kong government. Periclimenes demani, a small species of shrimp, resides in this grass.

Historical event

On 8 June 1857, a British naval frigate encountered pirates at Crooked Harbor, 70 men leapt overboard and were massacred on land.