This is Hell 7/8: Chinoike (Pond of Blood!). I nicknamed this one the "Bloody Mary," due to the fact that the trees hold an uncanny resemblance to celery stocks. The spring is filled with clay which gets super heated, turning the water and steam red. They also sell red clay ointment which is said to cure a variety of skin diseases. I didn't buy any - the 500 Yen admission was ripoff enough!