First thing's first. I've been diving with Mantas before at cleaning stations, so I might be jaded. But I feel like the Manta experiences on the Big Island are a bit over blown. We took our family of 5 on the 5:30 Manta experience with Ocean Encounters. They were really professional and also fun, but were apparently hampered by global neoprene supply issues. I was given an XL wet suit top, which was WAAAAY too big for me. Luckily, I had my shorty wetsuit and used that, which was probably a lot warmer than a giant XL top, but I was still shivering cold. We has one manta barrel roll through the plankton attracted by the LED lights, and it was stunning, but frankly, there are so many boats out there. Everyone must compete for the mantas, which seems not great. i do have to say that I called ahead to inquire about how good visibility was (My daughter was freaked out about the black abyss), and the staff was very reassuring that yes, the bottom is visible, even at night. We did enjoy, but the timing is really hard. We had to leave our hotel at 4:45 or 5 to make the 5:30 meet time, and it ends at 8:30 or so. Many, many restaurants are closed after 9, so getting food is an issue. Ocean Encounters offers an 8:30 option, and I do think that is likely better than the 5:30 option.