In 1,200 odd dives in the Caribbean, I have seen Mantas on a dive.... once. And I am still not 100% sure that they weren't devil rays (we didn't get close).
I think there are better Manta sites on the Central American mainland (probably on the Pacific side), but everyone here says the same thing: go to Hawai'i for Mantas.
I think there are better Manta sites on the Central American mainland (probably on the Pacific side), but everyone here says the same thing: go to Hawai'i for Mantas.