I did the Night Manta and Expedition South Kona trips on consecutive days and both were excellent. We were in the water for about 40 mins before a manta finally showed and the driver, Kevin, was nice enough to extend our time a little to make sure we had enough time with the manta. The experience was amazing and the manta swims right in front of you. A must for Kona for those who enjoy snorkeling. The divers, John and Melissa, and the boat operator, Kevin, were all very friendly, knowledgeable and helpful.
I went out on the Expedition South Kona Cruise the next morning with Lauren and Skyler. Also very friendly/knowledgeable/helpful. We stopped to swim with a pod of spinner dolphins on our way down the coast, and also saw humpbacks breaching/fin slapping, which was awesome. Went to Two Step first (Honauna Bay) and saw 3 turtles, sleeping white tip reef sharks and all kinds of fish. Captain Cooks was similarly amazing, although we did not see any turtles here. Stopped in some sea caves on the way back.
Overall, both trips were easily worth the money and are highly recommended for anyone interested in a unique snorkel experience.