This is what it looks like after cleaning it out the best I could. It's not deep but she doesn't like it messed with at all. I washed it the best I could and it's not hot or swollen. BO checked it before taking her out in the morning and she's only sensitive if it's being poked or scrubbed. She's walking fine and doesn't seem to notice it. It's still pretty dirty but she's too tender when it's messed with to let me do anything other than hose it. When I attempted to get in there an clean it I had a hoof two inches from my face even with the BO holding one of her fronts.
I want to say from feeling what I could it's maybe a couple millimeters deep. I can fit the tip of my nail in there and I don't have long nails.