This is where the Yamabushi used to accomplish the purification water ritual (misogi 禊) before climbing Mt. Haguro when the roads didn't exist yet. The red bridge that connects the area with the small shrines and the Suga Falls is called Shinkyo 神橋 ("the divine bridge"). Before the 1870s, when Dewa Sanzan converted to Shintoism under the pressure of the government, the bridge used to be called Fudo no Hashi 不動の橋 ("Acala's bridge"), and the Suga Falls were called Fudo no Taki 不動の滝 ("Acala's Falls"). Despite its Shinto identity now, there are still Buddhist statues of Acala in front of the waterfalls.
To go there, get on the bus bound for Haguro-Gassan (bus timetable) and get off at Haguro Zuishinmon mae 羽黒随神門前.
You will need to go down Mt. Haguro's stairway to go there. The stone steps can be very slippery after the rain, so please watch your steps. Bring rainwear in case of bad weather, and water supply to prevent dehydration.
Some people find Mt. Haguro's exploration to be a very physical exercise. Please make sure you are feeling well enough to walk Mt. Haguro's stone steps.