There is a website which is useful for you to visit geoparks in Hong Kong. Recently, the local government agressively promote geoparks for their tourism. Surely, a few geoparks are worthwhile to pay a visit especially the sampans or kaito at Sai Kung Pier can take you there on boat! The sampan businesses can easily be found becuase they always hassle along the pier line.
There is a website which is useful for you to visit rock cravings in Hong Kong. In my opinion, visiting rock cravings is a bit time consuming to tourists. It is still good for expats and exchange students.
There is a website which is useful for you to inquire marine life in Hong Kong. In my opinion, visiting marine life in Hong Kong is a plus for expats and exchange students.
There is a website which is useful for you to find out hiking routes in Hong Kong. Hiking in Hong Kong becoming very popular amongst expats and exchange students in recent decades in Hong Kong. A prominent example is Lion Rock Hill. Another one is the monkey kingdom in Golden Hill (Kam Shan Country Park). The gateway to have a handshake (just joking!) with the monkey kings and queens is located at the entrance at the corner of Tai Po Road and Cheung Yuen Road.
For those need to purchase map, you may visit Survey and Mapping Office to seek out some maps useful for your expedition.