Sam tiptoes through the ferny forests of Purgatory. He's doing his best to be quiet, but eventually one of his giant feet steps on a twig with audible results. Some guy in a bedraggled potato sack outfit lunges at him and knocks him to the ground. Sam throws him off and takes his knife. When the guy charges him again, Sam lops off his head. Padalecki is doing his best to seem very frightened by the whole situation, but the Winchesters face worse menaces on the way to the gas station. Having to fight a single monster is practically a vacation for these guys.
Soon, he comes to the three entangled trees. With a backwards glance to make sure he's alone, he sets down his new P-knife and wrests a boulder out of a hollow in the trees' base. Air whooshes into the blackness beyond. "It's a rabbit hole," Sam pants. "This is nuts!" He picks up his P-knife, takes a step towards the trees and vanishes inside.
He emerges in what looks like any stony interior set we've seen on the show before, except for a few Greek columns placed here and there. It's dark except for the faint glow of a few torches along the walls. Which, you know, is actually sort of nice of the demons to provide. Sam takes off his watch and places it near his entry point, like Hansel dropping a bread crumb. What he doesn't realize at this point is that his entire journey is only going to be about 14 feet long. Pained moans and screams can be heard in the distance. As Sam rounds a corner, he finds a woman chained to a wall, her feet held over glowing hot coals. "I'm innocent," she says. "Help me!" A man in a nearby cell bears a bloody ring through the flesh between his eyebrows. It's supposed to be all "AH, HORRIFIC!" but people can get scarier piercings than that at the mall. In the next cell, Sam finds a young woman. "You came!" she says. "I've been praying for it forever!" She keeps repeating this, having lost her mind at some point, either before or after her eternal incarceration. Sam moves on.
While he does that, let's pause for a moment to reflect on how not scary this version of Hell is. It's nothing like the surreal chasm that greeted Dean with chains and meat hooks. Now, obviously, mocking up a CGI Hell where your actor is mostly staying still is a lot easier than trying to recreate the same when your actor has to actually move through the landscape. But, come on. This dungeon is a tame embarrassment! Even Crowley's bureaucratic nightmare of perpetual waiting was more frightening.