Since these waters lead out to the open Pacific, it's more likely that big ocean dwellers like pilot whales and whale sharks will swing by to feed along their travels. The story goes that more than twenty years ago, a local hotel installed underwater lights, which attracted photosynthetic plankton blooms, which in turn attracted hungry mantas. Nowadays, the arrival of feeding mantas has become a local ritual, and admittedly a bit of a scene. Most divers take a four-minute boat ride out into the bay and dive from there. Just when you begin to wonder what you're doing there, the mantas suddenly appear.
Mantas are harmless to humans.
These sites are more pristine than the heavily touristed sites. Aloha goes to some cave systems, and spots where rare endemic species can be found, or where larger pelagics are more likely to be seen. A two-tank afternoon is a general phrase, which, regardless of the time of day, means you'll dive using one tank, return to the boat, and find a new site where you'll use the second tank. Nevertheless, when I dove off the southern coast resort area of Poipu last February, I saw more green sea turtles in one dive than I've ever seen before. Huge and somnolent, they eyed us lazily as we swam up close.