Portlock Beach is one of those hidden gems of a location. It is located in East Oahu, around 25 mins from Waikiki. Because it is within a residential neighborhood, street parking can be limited and the beach is not very large. However, for a small group (up to 6 people) it offers a stunning backdrop with mountain and ocean views, coconut trees, and there are rarely any other beach users around.
Because the beach is not very big, the water level can get close to the shoreline so be prepared to get your feet wet during high tide. You can also see the backside of the famous Diamond Head crater and this is also a great location for Sunset Pictures.
Portlock Beach photographs well in the mornings or late afternoon/sunset. I would avoid midday which has harsh lighting and is also very hot.