One of the things my niece wanted to do for her birthday was check out this wave organ that her and her friends had tried to find but didn't succeed. I found the location online, and after a phone call once we showed up and still couldn't locate the actual place, the sweet lady on the phone was able to direct us to exactly where the wave organ was located. The entire wave organ was built from stones from a graveyard. When the waves come in, the various pipes produce different tones. The best time to go is at high tide and a full moon, one of which we went at, and the other of which had occurred the night previous.
On our way back from discovering the wave organ that even people who have lived in San Francisco for years don't know about, even when it's in plain sight by the Golden Gate, we discovered the Exploratorium. The Exploratorium is much more well known, however, I had never been. I was in awe of the beauty with this place as well.