Lihue is generally the first port of call in Kauai, whether you arrive by air or sea. Once a plantation town revolving around sugar, it has grown since the closure of the mill to become a hub for traffic into and off of the island—though despite modern conveniences there is no forgetting that this island is a dramatic place of beauty and enchantment. Lihue is still small and quaint enough to preserve this impression.
Check out the Kauai Museum for an overview of the island's history, from textiles to photographs and artifacts recovered from archaeological excavations on Kauai. When you know the difference between the Alii and the menehune say 'aloha' and emerge into sunshine. For more history, visit the Kilohana Plantation or one of Lihue's old churches.
After this brush with antiquity, head for the age-old allures of nature and an afternoon nap on one of the easily accessible beaches. Kalapaki Beach has gentle seas for a swim or a little body-boarding, or wander out past Ninini Beach for a look at the Ninini Lighthouse.
Stop for a glimpse of Wailua Falls north of Lihue, but for some tropical time without the crowds book a guided kayak tour around Kipu Falls or take a hike/swim/kayak trip up the Huleia River.
Kauai is at the north end of the Hawaiian island chain just above Oahu and 100 miles from Honolulu as the jet flies.