I highly recommend this company for the manta snorkeling. Mainly because of three reasons: The guides, the fact that they are on the green list for manta experiences (they commit themselves to certain eco-friendly rules) and the small group size. The latter was the most important part:
After our trip, we heard from our guides that the mantas didn't come to the normal spot the last nights and that many boat companies saw zero mantas all night. Because of our small group size we were more flexible. Thus, when the guides realized that the "real manta magic" wasn't gonna happen at the normal spot, we moved a bit on the ocean. Finally, the mantas came incredibly close, almost touching us. It was really a once-in-a-lifetime-experience.
Additionally, you get FREE photos made by the guides. Especially good if u dont have a gopro or something like that.