The Shade Isle Campaign
Giant Spiders' Nest
So many webs.
He turned back, and the party decided not to explore that area.
Months later, the party intentionally returned to this place while hunting for monster-lairs to loot. They discovered that this part of the forest was occupied by giant black widow spiders, including an enormous brood-mother of a spider with double hit dice and extra-potent venom. The heroes slew the spiders after a pretty nasty fight (and several were bitten, although they were able to stave off ill effects thanks to some potion of neutralize poison), and they found some treasure in a web-sac.