This is definitely a whole day trip (9am-10am start) destination! Make sure to have a solid amount of cash for the trip. (At least $300 HKD, especially if you want to consider taking a boat from hiking back to the sai kung pier. PLUS, theres an amazing little restaurant on Ham Tin Beach that has BOMB food but will cost around $50-$65HKD/dish CASH ONLY!)
This is the trail that leads you to Sai Wan Waterfalls, Sai Wan Beach, Ham Tin Beach for camping.
Take MTR to Hang Hau station. Exit B1 to the undercover minibus stop, take the greenmini bus #101 to the Sai Kung pier. Get off at the last stop at the Sai Kung Pier and walk over to the GREEN taxi stand. Tell taxi driver to take you to the Sai Wan Pavilion (show on Googlemaps for reference --- LINKED already in map). It'll cost around around $100-110 HKD CASH and around 15ish min drive to the destination.
Sai Wan Pavillion is the beginning of a hiking trail through the Sai Kung East Country Park and towards the beaches/camping areas. Hike is around 45 mins to the beaches. Intermediate level.
A personal list of places in Hong Kong I recommend all my family and friends to check out if it's their first time in my hometown! Whether it's only just one day or a week, pick and choose which places pique your interests and go for it. Happy exploring! Also, check out my next list, Places to EAT in Hong Kong, coming soon. Enjoy!