A: There's no place on earth where so many giant manta rays gather each night to feed on microscopic plankton than just off the Kona coast. But because mantas like to feed in the open ocean and due to the underwater topography off the island, getting to the mantas does involve a short boat ride. There are several sites that are best for finding the giant mantas. Depending on which site is selected, divers can expect a 20-45 minute boat ride, each way. Divers should also expect to ride in comfort, as the larger boats offer marine heads and spacious decking that can accommodate up to 22 guests.