Bali is a small island. Lembongan is an even smaller island off the south coast of Bali. I read Lonely Planet guides and looked things up on their website. Once while using their site I was redirected to a service called Get Your Guide and a Lembongan Island Snorkel tour showed up that seemed reasonable and was getting super-high ratings on TripAdvisor, so I booked it. The photo I showed a couple of posts ago of the snorkeler (my wife) is from that trip. I got some good photos and you can see them if you click here.
Not every photo is spectacular but they provide evidence that we saw some amazing things including a Manta Ray. It was pretty deep and there were quite a few people there, so it was hard to get a good photo.
On this tour there was a lot of time spent in transit. We were picked up at our hotel by car; then transported by fast boat to the island; then a bumpy short ride in the back of a truck; then a ride with eight other nice people to the three snorkel sites. It was all well organized and it turned out to be worth the effort.