If you want to see opposite sides of the Big Island (which you really must experience to appreciate the differences), the best way is to rent a car and drive.
After sightseeing around the Kauai by car, our muscles needed stretching: it was time for an excursion on the Wailua River. We rented a tandem kayak early one morning, launched, and paddled through flat water toward the Fern Grotto, a natural lava rock amphitheater used for musical shows. We arrived before anyone else, including the performers, docked, and went ashore to explore. Thick tropical ferns kept the setting dark, almost gloomy, but it wasn’t hard to imagine a performance enlivened with music, dance, and colorful costumes among the verdant vegetation.
Shuffling bare feet on the sands of Waikiki Beach and eating Polynesian food at luaus was fine relaxation for a day or two, but it wasn’t long before my husband and I needed to challenge our bodies a little more—not to mention escape ever-present crowds around popular attractions. Fortunately, the weather is perfect most days year round, and hiking trails are abundant on Oahu.