Visit the Kakaako Waterfront Park Beach

Although it's not exactly a beach–due to the total lack of sand–Kakaako Waterfront Park at least deserves an honorable mention among Oahu beaches as it sits on the seaside, it's a good place to enjoy Hawaiian outdoor activities, and surfing is fun for experienced wave riders.  It's also a great place to have some exercise, have a picnic, watch the sunset, enjoy a stroll after dinner, and my favorite: go blocking the ice.  This has been a popular Honolulu hang-out since it first opened in 1992 due to the easy access from anywhere in downtown.

Great place to take the family or group of friends to just hang out and chill.  It's kind of placed in a unique location (by the Children's Discovery Center and UH John A. Burns Med School).  If you don't know where you are going or unfamiliar with the Kaka'ako area then you might have a hard time finding the place but an easy landmark to spot is all of the Car Dealerships right in front of the streets that you can go into that will lead you over to the park.  As far as cardboards and sliding down hills, you have to have the right kind of cardboard and good technique to catch a perfect slide down the hill.