Kat O was formed as a result of violent volcanic eruptions. In the region there are also other spectacular geological landforms, like Monk Viewing the Sea, which was formed by weathering, and Kai Kung Tau. Kat O, which literally means an auspicious bay, is the northernmost island in Hong Kong with a history of 300 years and is home to 10 settlements that used to be inhabited by 6,000 people of 43 clans and 37 surnames at its height. Although there are now some ten households only, the villagers still insist on holding the decennial On Lung Dajiu, which attracts many people. Kat O Nature Trail starts at the geoheritage centre converted from a village school. Its latter part passes by a viewing point which overlooks the vistas of the island, Mirs Bay on the east and Sha Tau Kok on the west. Take the ferry from Ma Liu Shui Pier to Kat O and Ap Chau, and start your weekend geology excursion.