The spectacular waterfalls, mysterious jungles, emerald fields, and stunning ocean vistas along Highway 19 northwest of Hilo are collectively referred to as the Hilo-Hamakua Heritage Coast. Brown signs featuring a sugarcane tassel reflect the area's history: thousands of acres of sugarcane are now idle, with no industry to support since "King Sugar" left the island in the early 1990s. The 45-mi drive winds through little plantation towns, Papaikou, Laupahoehoe, and Paauilo among them. It's a great place to wander off the main road and see "real" Hawaii—untouched valleys, overgrown banyan trees, tiny coastal villages. In particular, the "Heritage Drive," a 4-mi loop just off the main highway, is well worth the detour. Once back on Highway 19, you'll pass the road to Honokaa, which leads to the end of the road bordering Waipio Valley, ancient home to Hawaiian royalty. The isolated valley floor has maintained the ways of old Hawaii, with taro patches, wild horses, and a handful of houses.
Any turn off along this coast could lead to an incredible view, so take your time and go exploring. Where there's a gorge there's usually a waterfall, and many of them fall into lovely swimming holes, so you might want to bring both hiking shoes and a swimsuit. Gas stations, stores, and restaurants are hard to come by on the coast, so it's a good idea to fuel up your car and your tummy before hitting the road. If you're driving from Kailua-Kona, rather than driving around the northern tip of the island, cut across on the Mamalahoa Highway (190) to Waimea and then catch the 19 to the coast.
If you've stopped to explore the quiet little villages with wooden boardwalks and dogs dozing in backyards, or if you've spent several hours in Waipio Valley, night will undoubtedly be falling by the time you've had your fill of the Hamakua Coast. Don't worry: the return to Hilo via Highway 19 only takes about an hour, or you can continue on the same road to stop for dinner in Waimea (30 minutes) before heading back to the Kohala Coast resorts (another 25 to 45 minutes). Although you shouldn't have any trouble exploring the Hamakua coast in a day, a handful of romantic B&Bs are available along the coast if you want to spend more time.