We've seen Mantas at least once on every trip we've taken to Maui (we're on our 10th trip this year). There's a spot called "Manta Point" that's a Manta cleaning station where a few operators will take you, which we're looking forward to diving this year. We also see Spotted Eagle Rays on a regular basis as well. I'd say on at least 80% of our Molokini dives we see White Tip Sharks, and for far more sharks (including Hammerheads), you can go to Molokai while staying on Maui. We've been treated to seeing Bottlenosed Dolphins above and below the water at Molokini and Spinner Dolphins above and below the water on Lanai. If you're lucky you'll get to dive with a Monk Seal as well.
I guess to me that's one huge advantage of Maui...you can dive 4 islands (Lanai, Molokini, Maui, and Molokai). And when you go in the winter, the largest concentration of Humpback Whales in Hawaii are found in the channel between these islands. Being able to hear and FEEL whale song is an amazing experience, and every dive charter becomes a whale watching excursion. I am every hopeful that one day I'll see one UNDER water.
One day we'll get to Kona for the Manta night dive, but for now the advantages of diving Maui keep pulling us back....well that, and our timeshare there!
You should get to Kona to try more than just the night dive... lots of great diving, no regular afternoon wind issues so the diving's all day, great viz, lots of excellent dive sites are available without getting beat up on a boat ride for 30-45 minutes... Nothing wrong with Maui, but Kona's got a LOT more going for it than just the manta dive.
