Sutro Baths Park, located in San Francisco, is a cool spot to explore. Once a massive saltwater swimming pool complex, it's now a collection of ruins that tell a fascinating story. Back in the day, it was the world's largest indoor swimming pool establishment, built by the wealthy entrepreneur Adolph Sutro. But, unfortunately, the baths struggled to stay afloat due to high costs and eventually burned down in 1966. Today, all that remains are concrete walls, blocked-off stairs, and a tunnel with a deep crevice. It's a unique place to visit and imagine what it must have been like back in its heyday.

Dog-friendly: Yes, but must be kept on leash and well-behaved

Soft adventure: Yes

Fees: None

Seasonality: All seasons