Walk to the very end of the jetty that shelters the Marina's small boat harbor (the Exploratorium lists the address as 83 Marina Green Dr.) and you reach the Wave Organ. It's a wave-activated sound sculpture where pipes run down into the bay. As water moves in and out of them, they send up low, gurgling notes.
Who built it
The Exploratorium says the Wave Organ was conceived by artist Peter Richards and built with sculptor and master stonemason George Gonzalez. Richards was inspired by a recording artist Bill Fontana made of sounds from a vent pipe at a floating concrete dock in Sydney, Australia. A 1980 National Endowment for the Arts planning grant and a prototype at the New Music '81 festival followed.
Exploratorium founder Frank Oppenheimer led fundraising. Construction began in September 1985, seven months after his death, and was finished in May 1986. The sculpture was dedicated that June to his memory.
What it's made of
The jetty itself was built with carved granite and marble taken from a demolished cemetery, and those old stones form the sculpture's terraced seating. The Exploratorium counts 25 organ pipes of PVC and concrete set at different elevations so they work as the tide rises and falls. Atlas Obscura compares the effect to the sound in a conch shell: a column of air resonating inside each pipe, with the pitch changing as water moves in and out.
When to go
Both sources say it sounds best at high tide; Atlas Obscura says the acoustics only work when the tide is in. Check a tide table before you go. The sound is subtle, so give it a few minutes. Atlas Obscura notes there's parking in the marina a short walk away and that Crissy Field is close by if you want a longer walk.
Good to know
It's outdoors and free. Wear layers and watch your footing on the uneven stone.
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