It's true that mantas and whalesharks can be seen year-round in the Maldives... but not at every site, and not at any time... all at once. I get comments like this fairly regularly.
The atolls differ- some are reknowned for grey-reef sharks, some for mantas/whalesharks, some have good biodiversity, some are remote, some are now getting crowded, some have surfing spots. It's all the Maldives, but we're talking about a country over 900km in length, 26 atolls, almost 2000 islands in a 90 000 square kilometer area.
Manta feeding frenzies like those
sometimes seen in Hanifaru are actually quite rare- specific conditions must come together and those conditions are either not well known or impossible to predict (like predicting the weather- they get it right maybe half the time at best).
I consider Laamu Atoll a good atoll for grey-reef sharks however the numbers increase dramatically in the NE Monsoon (Dec-April). I still see a couple at this time of year but not 25+ like in the 'shark season'. For my money, if you want whalesharks, the most regular spot is Maamigili, South Ari Atoll. Mantas frequent this area during the NE Monsoon, but individuals can be seen at any random time during the year.
Right now, at this time of year, mantas are more on the eastern fringes of the atolls. We had a couple yesterday playing around in very shallow water (3ft) on the outer reef.
Given the strength and consistency of the S/SWwinds this last fortnight, I'd imagine sightings are increasing at Hanifaru right about now.
This pdf. may provide some information, but it's important to understand that nothing can be even remotely guaranteed when it comes to aquatic animals, as so little is known about their environment.
http://www.mantatrust.org/wp-conten...an-Manta-Ray-Project-2011-Research-Report.pdf