Being on an island is so nice since you are obviously surrounded by ocean all around. This makes for endless beaches to go explore. In my time on Bali, I made my way to a few "secret" beaches. They were amazing and had way less people than the well-known easy to get to spots.
The first one I went to is called Green Bowl beach. The descent down the cliffside is about 75 meters with steps made by locals over the years. This steep climb down makes it a destination that not all your typical beachgoers will make it to. It's best to go at low tide so there is more space on the small patch of beach that's there. There are many huge rocks that you can adventure to if you don't mind making your own path through them. The water at this spot is a beautiful crystal blue color.
Another secret beach I love is called Nyang Nyang beach. This one has an even larger descent down than Green Bowl and the path has no steps, just a dirt path underneath an umbrella of trees. I saw multiple monkeys on the hike down hanging out in the trees above. This beach has even less people, every time I've been, we were the only ones down there besides maybe one other couple!
The water is gorgeous here too, but there is unfortunately quite the collection of trash from the ocean washed up on shore :( The view from below almost makes it like a Jurassic Park looking scene. The hike down takes about 30 minutes from top to bottom, but I think it is well worth it!