Waterfall

 is the third area in Undertale that the protagonist journeys through, coming immediately after Snowdin and preceding Hotland. It is a dark, wet, and cavernous region, and houses residence for Undyne, Napstablook and their cousin, as well as Gerson's shop. Temmie Village and, subsequently, the Tem Shop is located in Waterfall. By reading the plaques aligned throughout Waterfall, the protagonist learns about the history of Humans and Monsters, as well as information about the nature of their respective SOULs.

Appearance
Mostly a dimly lit or completely dark area, the caverns and open regions of house many fields of Echo Flowers, houses, and the Garbage Dump. It is characterized by its blue, black, and purple color scheme, as well as being quite rainy or wet. Echo flowers and the water surrounding them display a unique bright teal color, which provides light in the dark region, alongside lanterns and glowing crystals.

Neutral and True Pacifist Route
After the encounter with Papyrus, the protagonist makes their way to Waterfall. Shortly after arriving in Waterfall, the protagonist will encounter Sans operating one of his patrol outposts. The protagonist can choose to accompany him to Grillby's for a meal (More information about this encounter can be found on the "Grillby's" page).

While progressing through Waterfall, the protagonist will encounter Undyne, Papyrus's mentor, leader of the Royal Guard, and fervent hunter of humans. Undyne stalks the protagonist, and repeatedly attacks them, although the protagonist always manages to evade capture either by dodging her attacks and running away or when Monster Kid inadvertently interferes with Undyne's attempts to capture the human.

After an encounter with Undyne, the protagonist will find themselves in the Garbage Dump. Here, the Mad Dummy, an invulnerable ghost residing in a dummy, will attack the protagonist, barring the way forward. Upon leaving the Dump, the protagonist will be met with Undyne's house, Napstablook's house, the Thundersnail mini-game, and Gerson's shop. Temmie Village along with the Tem Shop, which can come to sell the Temmie Armor, the strongest armor obtainable in a Non-Genocide run, can be found nearby.

The end of Waterfall is marked by a formal encounter with Undyne, during which Green Mode is introduced. After Undyne is defeated, whether it be by sparing or killing, the protagonist will be allowed to enter Hotland.

Genocide Route
After killing Papyrus, progression through Waterfall will be largely similar to that of a Non-Genocide run. The only differences include the fact that all of the flower bridge puzzles will be completed in advance, while none of the Echo Flowers will recite any dialogue. Gerson will adopt a hostile attitude toward the protagonist, but remain confident as he is aware that his status as a shopkeeper prevents him from being attacked. The Tem shop will not sell the Temmie Armor. The Mad Dummy's hatred of the protagonist will transform it into the Glad Dummy, gaining a corporeal form in the process allowing it to be defeated in one strike.

Monster Kid will eventually inform the protagonist that Undyne told them that the protagonist was dangerous. However, Monster Kid questions the protagonist, believing it is not true. The protagonist will approach Monster Kid with hostility, in which Monster Kid then stands up to them. A battle will promptly begin with the Monster Kid, where the protagonist may choose to abandon the genocide run by sparing the Monster Kid, or begin the first real boss fight of the run by attacking. Attacking will cause Undyne to take a savage blow meant for Monster Kid, which depletes all of her HP. Instead of dying, however, her innate Determination allows her to weather the attack and reform as Undyne the Undying. Killing her will grant passage to Hotland.

Features

 * Undyne's house
 * Napstablook's home
 * Napstablook's cousin's home
 * The Snail Farm
 * Snail Racing Game/Thundersnail
 * Echo Flower Fields
 * Gerson's shop
 * Temmie Village
 * Temmie Shop
 * Onion-san
 * Ferry Monster
 * The bird that carries you over a disproportionately small gap
 * Piano Puzzle and Artifact Room
 * Gaster/Mystery Man Room (Fun values only)

Puzzles

 * See Waterfall/Puzzles.

Trivia

 * When the southern wall down and to the right of Sans's expensive telescope or directly below the nice cream corridor are inspected, the text "The gems on the southern wall shine in a spectacular pattern." "It's a nice thing you can see the southern wall from this angle." appears. This text is one of the many RPG-related jokes in Undertale, as the southern wall is usually impossible to see in most RPGs.
 * By inspecting the waterfall in the room with the falling rocks, the protagonist can discover a hidden camera, which is later found out to be controlled by Dr. Alphys to follow the protagonist's every move.
 * There is a glitch in which if the protagonist kills Papyrus, where they first encounter Undyne while hiding in the grass, if they move left instead of right, Papyrus will come into view, standing on the side where he would normally appear during the Neutral and True Pacifist Route. This bug was fixed in the 1.001 patch.

Waterfall Водопад 瀑布