Located just off the eastern shore of Bali, Indonesia, is a small island called Nusa Lembongan. It is a great place for a day trip if you're vacation in Bali, and it's only a 30-40min boat ride from Sanur. There is a boat that will take you between the two islands a few times a day.
Once arriving on the shores of Lembongan, it is best to rent a scooter for the day (US$6). There are only a few roads on the island, so it is impossible to get lost, and the beaches are well marked by signs. Unlike Bali, there is no traffic on the island!
We set out around the island in a counterclockwise loop. We stopped and watched the villagers drying colorful seaweed along the shore (this is used to make ice cream). We stopped at the mangroves for a fresh seafood lunch, beach time, and snorkeling. And then explored the many picturesque beaches around the island. Our favorite was "Dream Beach," and it lived up to its name.
Be sure you don't lose track of time on this paradise of an island. It's easy to do, and we almost missed our return boat back to Bali that afternoon!