In the great oak tree.
Dawn breaks across the land, the sky and its sparse clouds lit in fiery hues by the rising sun. The interior of the great oak tree is dark and cramped. The bark is cool and rough to the touch. Some industrious person has patiently and lovingly carved out the interior so that a small platform is available to sit upon. Another shelf, somewhat higher, is perhaps a good place to put a small candle. The tree seems to be hollow quite a ways up but it is hard to tell exactly how high up it goes, since it is so dark. The beginnings of a ladder up the inside of the tree seem to be carved to one side, and a small hole in the trunk of the tree might just be big enough for someone to crawl through. A bright beam of light peeks through the hole.
I've tried bringin candle and placing/putting, turned on nightvision, tried to enter/crawl/squeeze the hole, and climb the ladder. None of these things are interactable.
I've found a hole in Lodi as well, but can't interact with it.
Are these not the black warren entrances? I tried secrets check many times too.
I've yet to find out where the magic cheese and wand is, maybe that's preventing entrance.