The reddish light of the sun didn't penetrate very deep.
Natural light from the central open space penetrates the halls.
If there were stars, their light did not penetrate the thatch.
The windows were high up on the stone walls and the light did not penetrate to the floor.
The moon was high, but its light did not penetrate the darkness of the trees.
The forest looks like a huge dark vessel into which even light can not penetrate.
Little natural light penetrates to the bottom, so their visibility is limited to a few feet.
The door was open just a crack and the light did not penetrate at all.
It was also dark since the natural light could not penetrate far.
"You should all find a place to rest, be sure no light can penetrate."
