Another vote for Kona, although nobody has mentioned Yap, and it's also a dedicated Manta destination that is pretty easy to include on a trip to Palau.
Here is a little mini report I did of my Kona night dive:
The coolest dive I've ever done. You leave the shop about 3:00 and do a late afternoon dive at the same location as the night dive, in order to get used to the location. Even during the day, we had at least 6 manta sightings, more than I've ever seen in one dive before.
After the afternoon dive, more boats start to show up. There are already 22 divers and snorkelers on our boat, and by dark there are 6 OTHER boats tied up, filled with more divers and snorkelers.
When it is completely dark, the divers all hit the water and go to a pre-determined spot on the bottom at 40 feet deep, and aim all dive lights up. All the snorkelers go to the same spot, and aim their lights down.
All this light attracts plankton, and all the plankton attracts feeding Mantas. I was first in the water and first on the bottom. Within a minute, the first manta cruised by. It was phenomenal. The larger ones are 12 feet across and weigh over 1000 pounds.
Within 20 minutes, after all the divers and snorkelers got on station, we had 26 mantas in a feeding frenzy above our heads. They would approach you directly, get within 3 feet of you, and pull up at the last second and actually graze the top of your head with their bellies. The would find places with lots of plankton and do 6 or 7 back loops to stay in the feeding area.
We were not allowed to touch them, but they would gently touch us in the course of feeding. At almost any moment you could reach up and touch one if you wanted to.
The dive lasted over an hour. I was exhausted from the excitement. It was beyond imagination.
The first four shots are from a pass-by during the afternoon dive.
Then the night dive. At first there was a school of fish feeding above us, the the first manta swam into the school and scattered them
Then the mantas began appearing out of the darkness from every direction
Sometimes they would line up in the middle and do coordinated steeply banked turns. It was graceful and beautiful. This shot was taken in front of me, not pointing up. The closest manta is doing a 90 degree banked turn.
Here are two mantas intersecting within 4 feet of me, and another approaching close behind. I was using a fisheye wide angle lens, so all the mantas are actually closer than they look.
When two mantas would approach each other head on, they would both pull up at the same time and sometimes belly-bump. I happened to be right underneath this one.
The next photo has a lot of bubble interference, but I cranked up the ASA and lowered the aperture for a few shots just to try to capture some of the congregations of mantas above us. They were well out of strobe range so what you see is illuminated by the nearly 100 dive lights in the water. If you look closely you can parts of 8 mantas in the same shot.
