Pinyin: Dà shí yù
English: Big stone pass
Coordinates: 40°21'13"N 117°59'45"E
There are two ways to get here, neither of which are by public buses since they don't come this way. Both places are roughly 12-13km from Zunhua bus station and a taxi ride should cost no more than 30 kuai.
1. Take a taxi to Chanlin Temple (禅林寺), a temple with supposedly one thousand years of history (although reconstructed after the Japanese burnt it down sometime in the 40s). Ticket costs 50 kuai. Getting to the Great Wall from here is a bit far as you have to walk up and down a mountain before getting to it.
2. Take a taxi to Dashiyu itself. If the taxi driver doesn't know how to get there, it's roughly a kilometer northeast of Matiyu (马蹄峪) village. There's no ticket to my knowledge and it's closer to the Great Wall than coming from Chanlin Temple.
Upon seeing this, take a right. Keep going straight down the road for about a kilometer and then you'll come across an open space on your right. Just walk through the gorge and you'll eventually see the Great Wall.
And that's pretty much it. I would've bothered going up the other side but it didn't seem stable and the smog was terrible that day.
Be aware that if you want to go back to Chanlin Temple, you must walk up the mountain opposite from the mountain the Great Wall is on. If you just exit to the right and walk through the gorge, it won't take you to the temple, and if you have no transport waiting for you it's a long walk back to the main road where you can take bus 1 back to Zunhua bus station for 2 kuai. (a 90+ minute walk).
So this is interesting. This is back on the main road where you can take bus 1, and it says Jiufengshan is only 5 km away