There's a hidden beach at the far west end of O'ahu that is relatively unknown and uncrowded, it's the four lagoons at Ko'Olina Beach. Part of the reason it's unknown is the beach is on a ritzy hotel and the Nanakuli/Farrington area acquired a bad reputation. Unattended cars have a habit of getting broken into, but don't let that stop you from visiting this beach. Though the lagoons are public, Ko'Olina is a private resort and since parking is on the property of the Ko'Olina resort, the parking lot is patrolled for added security. Good thing about this beach is the parking is free, the waters are calm, and the beaches are relatively uncrowded.
Ko'Olina Beach is located at the far south-west end of the island. If you're in Waikiki expect to drive for about 1 hour to get here. It's not the distance, but the traffic that slows you down. The beaches have showers, bathrooms, and nearby restaurants, but there are no lifeguards on duty. However, the beaches are sheltered by man-made lagoons, making this ideal for kids or new swimmers. As a precaution, don't leave your valuables in the car despite the parking lots being patrolled.
Ulua (fish) Lagoon #4. This is the busiest beach, being closest to the parking lot. It's easy to spend the entire day here, just remember the parking lots close at sunset.
Ulua Lagoon #4. This was the busiest beach of the four, being closest to the parking lot. However, this beach is not as crowded as Waikiki Beach. There's a path that runs behind all the lagoons and goes all the way up to the Ko'Olina Resort.
Walking down the path you come to Na'ia (dolphin) Lagoon #3. I believe the beach chairs are reserved for the hotel guests, but it's still a great beach...
..and a great view. Just watch out for the sharp coral and rocks. As you can see, the waves are not ideal for surfing. And be careful if you go past the lagoon, the current can pick up here.
While you're by Lagoon #3, you can stop by Longboards for a bite to eat or drink.
Continuing on the concrete path to the resort, you reach Honu (sea turtle) Lagoon #2. This is the stereotypical Hawaiian beach: soft sand, gentle waters, and grass umbrellas. Honu Lagoon was the most quiet and least crowded of all the beaches.
Continuing on the path, you reach Kohala (whale) Lagoon #1. In the background you see the J.W. Marriott Ihilani Ko'Olina Resort and Spa and the Aulani Disney Resort and Spa. The Disney resort is new, I think they finished construction just last year. The Ko'Olina Marriott has been here for awhile and is one of the top hotels on the island. It's louder here, I think the music came from the Disney hotel, maybe they were doing a show.
But wait, there's more. Keep walking to the end of edge of the resort property and you'll see a sign that directs you to a public beach
Follow this path around the bend to the shore.
And here is Lanikuhonua Beach. This is a hidden beach, off the beaten path and away from the crowds. I wouldn't call it a "hidden gem", it's not like Lanikai Beach, but it's quiet and less crowded than the Lagoons. The waves picks up a bit at this beach, since it's not sheltered and the rocks are sharp.
Despite the soft sand, this beach is rocky. Not the best beach for swimming or wading. However, the rocks make great tidepools and you can see fish, crabs, or even moray eels. All in all, this is a great beach to check out and spend the day.