Tulamben is where the USAT Liberty was sunk by the Japanese. It washed up on shore and stayed there until Agung erupted in 1963. It's less than 20 feet off shore and 10–30 ft deep, depending on the tides. It's also created a natural reef.
The colors can't compete with the Caribbean when I was little, but it's very cool to be able to snorkel a wreck. I saw all kinds of parrotfish, blue sea stars, a garden of sea snakes, and a decorator crab that looked like a giant tarantula.
But the most amazing sight was watching local women carrying oxygen tanks balanced on their heads. Here's a picture taken by Andy Fraser: http://www.flickr.com/photos/andywfraser/4959401397/
They earn 10,000 rupiah per tank round trip or about 80 cents. This is higher than the minimum wage in Indonesia, but is completely dependent on weather and tourism.
(I did take photos with my underwater camera, but I don't have a way to connect them to my iPad. I'll post them if any come out.)