Blook Acres is the area found north of the "Quiet Area" intersection in Waterfall. This area contains Undyne's house, Napstablook's house, Mettaton's house, and the snail farm where the protagonist can play a game of Thundersnail.
The home of Undyne, which is accessible after the protagonist spares Undyne. The exterior of the house resembles a fish, with a fish mat in front of the house, which is similar to Undyne. Outside is the Mad Dummy, and Papyrus after sparing Undyne. Talking to Papyrus triggers the date with Undyne. After cooking with Undyne, the house catches on fire permanently and becomes inaccessible to the protagonist. Undyne then relocates to live at Papyrus and Sans's house in Snowdin, and Undyne joins Papyrus in his phone calls to the protagonist for the remainder of the game.
The home of Napstablook, accessible to the protagonist after Mad Dummy's battle. Inside, along with Napstablook, is a fridge, a television, a spiderweb with a flyer for a spider bake sale, a computer open to a music-sharing form, and three CDs, labeled "Ghouliday," "Spookwave," and "Spooktune." These songs continue to play after the protagonist leaves Napstablook's house. If the protagonist walks in the quiet area while one of these songs plays, a unique encounter with Aaron and Woshua triggers.
The house next to Napstablook's house, which is unlocked using the Mystery Key. This key can be bought from Bratty and Catty for 600G. Inside is an entirely pink interior, with completely pink and sparkly accessories. There is a book on top of a bed, a carpet, a poster, a single window, and a television, which are all inaccessible to the protagonist. There are six diaries on the floor, which detail the story of Napstablook's neighbor, a ghost who wanted to perform and become corporeal. This soul was then put into the body created by Alphys, which became Mettaton.
The Blook family business is run by Napstablook. According to them, the place used to have a large amount of business, until their primary customer (assumed to be Toriel) stopped coming. Currently, their only customer is "some hairy guy that comes once a month"; this customer is assumed to be Asgore, who keeps canned snails in his fridge. The first pen has four snails that the protagonist can interact with, while the second pen, where the protagonist can play a game of Thundersnail, has three racing snails.