BETA PHOTO: The Bridge Boulder, Wall Boulder, and Canyon Crest...
There are 3 boulders in this area. There might be some more further up stream but Iíve just found 3 so far. 2 are pretty close to each other and 1 is down a different stream. The boulders are granite and are pretty featured. Some holds polished smooth, but most are pretty rough. The boulders are nothing special, but cool if you live near by and want to take a hike after work and get a few short laps in.
The closest city is Altadena. From the 210 near La Canada and Pasadena exit Arroyo Blvd/Windsor Ave, head north towards the mountains, go about 1 mile and park on the left in the small lot just before the gate and where the road turns right. (Right by JPL). This is a popular parking lot for hikers and mountain bikers and you do not need a forest adventure pass.
For the Bridge Boulder and Wall Boulder From the parking lot after about a mile of walking the asphalt turns to dirt and splits into a Y near some buildings. Stay to the left. Hike another 1/4 mile to the wall boulder on the right or hike another 1/4 mile past that and cross over the second bridge and go down to the boulder about 10 feet on the left.
For the Canyon Crest Boulder You can approach this 2 ways. From the JPL parking lot walk 3/4 a mile then turn right up the first stream. Then hike about another 1/2 mile crossing the stream several times and then youíll see the boulder on the left side.
Or the lazy way, exit the 210 at Windsor, Right on Woodbury, Left up Lincoln, then turn left on Canyon Crest. Go about 1/2 a mile and park in a small turn out on the left or right. Then walk down into the canyon and downstream and youíll see the boulder.
Mountain Project's determination of some of the classic, most popular, highest rated routes for Arroyo Seco Boulders: