Part of the land in Hong Kong is formed by sedimentary rocks. As a result of a combined effect of the work of waves and change of sea-level on the lands and rocks, funny and spectacular features can be found on the coastline of many outline islands, e.g. Robinson Island, commonly known as Ap Chau(duck island).

Another famous and attractive island is Port Island. It is composed of red sandstone that makes it dressed with a mysterious red suit.

Rhyolite, a kind of volcanic rocks, form another spectacular senery. Hexagonal columns growing from the sea form the Nine-pin Group.

Therer are some more ...