Some 4 million coffee trees grow on 3,100 acres of former sugarcane fields from Lawai Valley to Eleele, making Kauai Coffee the largest producer of coffee in Hawaii—and the United States. Kona coffee fans might sniff at the fact that the beans are machine-harvested, but it’s surprisingly sustainable for such massive production, with 2,500 miles of drip-irrigation tubes, water recycling, cherry-pulp mulching, and other practices. You can learn all about the coffee-growing and roasting process on a free short, self-guided or guided walking tour, on the personalized, hourlong “Coffee on the Brain” tour ($20), or from a video and displays in the free tasting area behind the gift shop on a covered porch. Everyone heads to the latter first: How better to determine the difference between coffee varietals such as Blue Mountain, yellow catuai, or red catuai beans in an equally wide array of roasts and blends? A small snack bar in the tasting room helps take the edge off all that caffeine.