Honolulu's sights divide between the historic core downtown — Iolani Palace, Kawaiaha'o Church, the Kamehameha statue, Washington Place — and the outdoor experiences that spread across the island. Diamond Head is the essential hike: short, steep, and with views that explain why the city exists where it does. Pearl Harbor requires at least a half day and ideally more if you visit the Missouri and the Pacific Aviation Museum alongside the Arizona Memorial.
Further afield, Hanauma Bay demands advance planning (reservations fill weeks ahead) but delivers snorkelling that rivals anywhere in the Pacific. The North Shore is an hour's drive but a different world — surf breaks, shrimp trucks, and the small town of Haleiwa. The Bishop Museum covers Hawaiian and Pacific culture better than anywhere else, and Shangri La's Islamic art collection, accessible by tour through the Honolulu Museum of Art, is the most surprising attraction in the city.