I was floating in the wide saline lagoon of the Grand Hyatt Kauai, drifting along on my back. Buoyed by the semi-salty water, I watched the palm fronds waving in the trade winds above me, silhouetted ...

Not all sinkholes are created equal. While many of our planet’s natural pits and crevices are dank and inhospitable, some contain inviting pools of crystal-clear water, are surrounded by spectacular ...