Tonight was a blast. We did a late afternoon dive up at "Garden Eel Cove" off the Kona airport, which is the home of the manta dive. I captained the boat for dive one and did the night dive with the mantas.
We had one manta looping under the boat feeding under our floodlights while we were putting our divers in. Moving on over to the site where the dive operators set up we had 2 mantas right away. There were four within about 10-12 minutes and the other two arrived minutes later. We bascically had 6 mantas for the better part of 35-40 minutes of so 'til the dive groups began to split off.
People are often surprised by this dive as they are expecting to see a ray or two or more swim by a few times and that's it - hardly the case on a decent night - Tonight we had 5 boats of divers and snorkelers sharing the 6 mantas, my guess is that everyone who dove tonight had mantas within arms length of them for a solid 10 minutes as the mantas swam from group to group, with mantas within 20-30 feet of them, well within visual range, for a full 35 minutes at least.
It's an amazing dive, and a great snorkeling event for non-divers. I'd consider this to be probably the single biggest "must do" activity in Kona for those who enjoy the water and want something more than just the typical snorkeling or dive.
Here's a photo of a smallish White Mouth Moray. These are our most common moray. Color paterns are basically spotted, but the white mouth is always there even if the spot pattern may vary from eel to eel. These guy are relatively harmless under normal circumstances. Eels have very small gill openings so they can crawl through, and back out of, coral formations. They have to actively pump their gills to breath, hence the typical open mouth that some people think might be a threatening behavior.