There is an amazing wreck dive, that is absolutely worth doing, off of the eastern side of Bali. The USS Liberty sunk in a storm during WWII and lays no more than a few meters from the shoreline in the tiny town of Tulamben. With something for everyone, the Liberty's stern rests at about 30 meters while its bow can be explored at about 5 meters depth. Even snorkelers can enjoy. On a good day you will see sharks, huge schools of jacks, morays, rays, various types of sea slugs, crabs and hundreds of other ocean creatures. There is also a decent amount of coral buildup on the wreck and the ship itself is in recognizable condition making it great for wreck enthusiasts and creature lovers alike.
Tip: While most shops on the island will dive this site its best to go to Tulamben yourself and stay at one of the resorts right on the beach. Rent a tank and gear and simply walk out and dive at your leisure. Perfect if you get seasick and want to avoid the boat, also a good way to avoid the crowds!