Boulder Canyon contains a waterfall and some cascades, as well as a little loop trail* you can hike. It isn’t a state park, just a local area in Vestavia Hills, Alabama. You find the trail head by driving through a residential neighborhood in Vestavia Hills, Alabama. Try 1469-1427 Merry Fox Ln, Vestavia Hills, AL 35216 as an address. If this takes you to an area with an elementary sports field, you’re in the right place. This is worth visiting if you’re anywhere near Birmingham, Alabama on a trip for any reason, and should only take an hour of your time to explore.
*I actually got a little lost on the loop trail because even with a map showing it in the parking lot there, part of the trail had some downed trees and I cut across the creek to “find” a different section of it, but ended up on what I presume was an unmarked hiking or walking path, confused the whole thing, etc, etc. I’m awesome like that. You can’t get too lost though with a major interstate on one side, a creek to orient on, and residential neighborhood to stumble out onto no matter what. This isn’t the deep woods. It’s in a city.