Wow! Wow! We had 30 solid minutes with close encounters from two manta rays (Amanda and Grayer). Amazing. They touched me multiple times; at first it was a bit scary, then I lifted my arms up higher out of the water because I didn't want to be touched anymore!
This tour is especially nice because it is small--only six people around a floating surf-board with attached attracting plankton lights. I noticed many other tours that had 20-50 guests at once, which I thing could not offer as much intimate time with these lovely creatures.
What was also surprising was the amount of plankton visible. Some wer luminescent. Very cool. Also, tons and tons of fish--I mean tons. Some little ones may nip at your feet.
Sign in took only 5 minutes. Then we had to wait 30 minutes for the tour to start. The provided snorkels are low-end, leak water into the tube, and have uncomfortable mouth guard; it's okay for the short floating experience, but bring your own if your prefer.
Also we heard many other people saying they saw manta rays for much less than half of the tour time. While I believe this is the best Manta Ray viewing site on the island, buyer beware of this kind of risk. We stayed at the Sheraton Kona (next to this snorkeling site) and nightly would see many Manta Rays from our room balcony. Highly recommend this hotel. Call the tour operator directly to get better ticket price.