Hong Kong is part of the karst limestone mountain range that runs through southern China, through Vietnam (Ha Long Bay), Thailand, and the Philippines.  For such a small geographical area it packs quite a bit to see between beaches, mountain treks, and unusual natural formations.  There's also usually a good restaurant at the end of every hike.

beaches

I was in Hong Kong from October 2014 - February 2015...so unfortunately I did not have the opportunity to properly enjoy any beaches.

HIKES

There's always a hill somewhere you can climb.  Many of Hong Kong's hikes are also easily accessible via public transit.  The most popular and easiest hike is Dragon's Back.

islands

CHEUNG CHAU
Popular weekend spot that feels oddly mainland Chinese.
LAMMA ISLANDS
A bit rustic, a bit expatty.
LANTAU ISLAND
It's more than just an airport and a cable car ride to the giant Buddha.