Kat O is located in the west of Mirs Bay. With an area of 2.35 km², it is the largest island in North District, the second largest being Wong Wan Chau (Double Island). Neighbouring islands include: Ap Chau, Ngo Mei Chau (Crescent Island), and Pak Sha Chau (Round Island). The village of Tung O (東澳) is located on its northwest coast. Its highest point is Kai Kung Leng (雞公嶺), which is 122 m above sea level.
The Tin Hau Temple at Kat O was estimated to be built in 1763. It is listed as a Grade III historic building. Part of the temple building was used for the Tat O School until the school was moved to a new location in 1957. A Pak Kung Shrine is also located in the vicinity.
There are 3 cannons located on the island. They are estimated to be made in the west, during the 19th century.
The Kat O Nature Trail spans 1 km long, stretching from the Kat O Ferry Pier to Ko Tei Teng (高地頂).
The Kat O Geoheritage Centre (at No. 142 Kat O Main Street) was opened in 2010 by Kat O villagers, volunteer groups and the government to raise public awareness of geo-conservation, as part of the Hong Kong Geopark.
- Hong Kong Geopark: Kat O Nature Trail
- Survey and Mapping Office, Lands Department: Hong Kong geographic data sheet
- K.W. Lai, S.D.G. Campbell & R. Shaw, Geology of the Northeastern New Territories, p. 15, Civil Engineering Dept, Geotechnical Engineering Office, December 1996
- Brief Information on proposed Grade III Items. Item #974 Archived 2013-09-22 at the Wayback Machine
- Welcome to 18 Districts - North District
- List of the 1,444 Historic Buildings in Building Assessment (as of 27 December 2013)
- "Crooked Island". web.archive.org. 2016-03-04. Retrieved 2019-05-10.
- Agriculture, Fisheries and Conservation Department: Plover Cove Country Park Archived 2013-09-29 at the Wayback Machine
- Time Out Hong Kong: "Secret Hong Kong islands", 29 Apr 2014
- Hong Kong Geopark: Kat O Geoheritage Centre
|Wikimedia Commons has media related to Crooked Island, Hong Kong.|
- Kut-O Chinese Association (Kent area) Website
- Pictures of Kat O: , 
- Hong Kong Geopark: "Lee Yuk Ying Introduces the Cultural History of Kat O to Visitors".
- Webpage about Kat O