Things to Do in and around Waikīkī
Diamond Head Crater Hike (view from top below)
Also known as Lēʻahi (Hawaiian for "brow of the tuna"), Diamond Head is a 760-foot tuff crater and is among Hawaiʻi’s most well-known landmarks. It was named "Diamond Head" because 19th-century British sailors thought the crater's slopes were encrusted with diamonds, which turned out to be calcite crystals with no monetary value. If you make it to the top, you can snap bird's-eye view pictures (see above) of Waikīkī and show them off to your family and friends. The best time to hike is 6 AM, since you don’t have to deal with the burning heat and tight crowds.
Open 6am - 6pm daily. Last hikers allowed in around 4:30pm.
Cost $5 per person (4+ years old), and $10 parking.
The entrance is located on the mountainside of Diamond Head Road across the street from Kapiʻolani Community College near 4200 Diamond Head Road. Click here for map.
See more information about Diamond Head State Monument
Go Surfing!

Don't be shy. Waikīkī is a great place to learn how to surf. The water is warm and the waves are usually small enough to comfortably learn on. There are plenty of companies that will teach you how to surf or if you are adventurous, you can rent a surfboard and try to learn on your on.
Honolulu Zoo
Did you just hear a monkey howl or the trumpeting of an elephant in Waikīkī? Not to worry, you are not hearing things! Located on the east end of Waikīkī just off Kapahulu Ave next to Kapiʻolani Park lies the Honolulu Zoo. The Honolulu Zoo surprisingly has many animals, and it is much larger than it looks. Great for 1 person or the whole family to enjoy. Don't forget to bring your camera.
For more information: http://www.honoluluzoo.org
Waikīkī Sunset and Afternoon Cruises
Can't get enough of those Waikīkī sunset views? Ride one of the catamarans on Waikīkī Beach, and go on a 1.5-2 hour cruise to watch the sun sink into the horizon and signal the end of a day. There's also the day cruise option, though taking the sunset cruise gives you a more magical experience.
There are a few boats to choose from these are just a few:
Enjoy drinks, pupus (appetizers), and live music at world-famous Duke's Restaurant on Waikīkī Beach
KCC (Kapiʻolani Community College) Local Farmer's Market
If you're craving fresh and budget-friendly local Hawaiian produce, then the Farmer's market near Kapiʻolani Community College, just outside Waikīkī near the Diamond Head hike entrance, is the place to visit. Definitely go to the Saturday market from 7:30 to 11 am and if you are trying to avoid crowds or can't make the Saturday market, there is also a farmer's market open from 4 to 7 pm on Tuesdays, though it is much smaller than the Saturday market. Reward yourself after a hike or long day with local food from the market. You deserve it!
Also, there is a smaller farmers market at Kapiʻolani Community College on Tuesdays from 4 - 7pm.
For more information: http://hfbf.org/markets/markets/kcc/
For information in Japanese http://hfbf.org/markets/markets-jp.html