After getting to Green Island you'll need to get some form of transportation. Most of the island uses electric scooters; a single charge on a 50cc scooter will get you all the way around the island. It was easy to rent both scooters and cars while departing the ferry in June 2017. Drive to the "Little Great Wall" tourist attraction and go south. Turn left to go east on first side road you reach and follow it down to a garbage dump. Leave the scooter at the end of the road and go down to water level. Hike north, easier at low tide, and around the point to the small beach that is visible from the Little Great Wall. The four ocean spires at the north end of the beach all have high enough rock quality to climb. According to Ron's Blog
it is also possible to follow a trail from the primary road down to the beach.