Saint John’s Island also known as Saint John’s is the largest of the Southern Islands in Singapore. It is located approximately 6.5 km to the south of the main island of Singapore, off the Straits of Singapore. It is accessible be taken by a boat from Marina South Pier. Wikipedia
How to get there: Catch a ferry to St John’s Island from Marina South Pier (S$18 for an adult round-trip ticket, S$12 for children).