Barber's Point Lighthouse - Must go! (Travel Instructions: From Honolulu, take H1 west to Exit 1 (Campbell Industrial Park). Take Exit 1, loop back over the freeway, and proceed south on Kalaeola Boulevard until it ends at Olai Street. Turn right on Olai Street and follow it to Barbers Point Beach and the Barbers Point Lighthouse. The lighthouse is owned by the Coast Guard. Grounds open, tower closed.)
One of the most beautiful hikes on Oahu, the Makapuu Lighthouse Trail has amazing views the entire way. And if you come here during the right months (December-March) you have a pretty good chance of spotting whales.