The important thing to remember about manta rays – 3,000-pound creatures with wingspans reaching up to 22 feet – is that they're born with their wings wrapped around their bodies, like manta-ray burritos. Want a little more? They gobble up to 300 pounds of plankton daily, by executing octuple backflips with their three-foot-wide mouths agape. The males also have "clampers" which have to be 1.5 inches long for them to be able to mate.
These are just a few bits of trivia you can pick up on your next Big Island visit by staying at the Sheraton Keauhou Bay Resort & Spa (bonus factoid: Keauhou Bay is where Kamehameha III, Hawaii's longest reigning monarch, was born in 1813). For that and more, you only need to stop by the Manta Ray Bar & Grill (soon to transform into Rays at the Bay) on any given night, when the hotel directs its broad beams at the water starting at 7pm, and a dozen or more of the creatures come to feed. You can observe or listen to the Sheraton's docent from its broad deck – an experience which combines nicely with pupus or a Mai Tai, or with an upward glance at the stars.
But if you're feeling water-friendly and a little frisky (Hawaii does that to you, after all), you can also sign up for a snorkel or scuba night dive to see a few of the giant critters face to face. Fair Wind Big Island Ocean Guides is based in Keauhou Bay, just outside the Sheraton, so your wing-flapping manta frenzy can continue into the night at the location of your choice.
Rooms at the Sheraton start at $169 per night. Manta evening snorkels are $99, and manta dives are $145, including gear. There's no entrance fee at the Manta Ray Bar & Grill, where the Manta Ray Martini costs $10, but fishing for your own plankton is free.
For general trip-planning information, see our Big Island destination guide.