This is the famous Cromwell’s Wall located on Oahu. It is a little bay/cove where people could come and jump off the wall, swim, and just enjoy themselves. This is not the case anymore however, as there is now a fence put up around the area that prevents people from coming in. A few people had hurt themselves pretty seriously and one person ad died from not jumping off the wall correctly.
This, along with a couple of other reasons were the main factors behind the state shutting the whole thing down. This place is also popular because it is located right next to the Shangri La, which is the Doris Duke Museum of Islamic Art. You could actually see the back of the museum and even walk up some steps toward the area. Again, this is no longer the case. This picture was taken before the fence went up.
We have more info on the beach and cove and would love your review of it here: https://lookintohawaii.com/hawaii/4180/kaalawai-beach-cromwells-cove-beaches-oahu-honolulu-hi