If you are up for some long walks in the jungle, you could jungle trek to Batu Kuching as it is a great place to capture gorgeous sunrise and sunset from the rocks. Depending on where you stay on the island, travelling to Batu Kuching may take half an hour or more.
There are yellow arrow marks on trees and rocks on the trek to guide you to Batu Kuching. Bring along a torchlight, drinking water and wear proper footwear when jungle trekking. Batu Kuching has a lovely snorkeling site so consider bringing snorkeling gears if you plan to go for a swim.
If Batu Kuching is not challenging enough for you, you could also go for a more adventurous trek to Batu Bulan, where you can see fish and turtles when you go snorkeling there.