It’s at the Santa Monica Rings (aka the Original Muscle Beach) right on the sand. The earliest it can be would be from the 1930’s as that’s when the adult playground was built.
For those interested in what is actually happening in the picture: The guy is swinging on the Flying Rings. If you take the gymnastics Still Rings and swing them, the sport is called Flying Rings. You could pump yourself up to those heights, or get a push and then pump yourself up further.
The Flying Rings were banned in the Olympics (and many other competitions) by the early 1960’s due to the great dismounts/flyaways the swingers could achieve (up to 20 feet high) as the chance of hurting themselves or dying was very high, especially in a competitive setting.
With that said though, that doesn’t mean people don’t play on them. The flying rings are alive and kicking to this day at the santa monica rings, and I play on them as well. Here’s a buddy of mine demonstrating what it’s like just a few weeks ago at a typical Sunday.
Now, back to the picture. Other than the clothes people are wearing, if somebody knows what buildings exist/didn’t exist in this picture, then maybe that’s another way to figure out what decade or year it’s from. It looks like the LAX control tower could be seen on the right side, down the coast. And I’m not sure what that hotel is on the left. Even the Original Muscle Beach looks very different. Who knows how many times those rigs were replaced over 80 years time. Only more proof that change is the only constant.