Nowhere is a completely empty, infinite white void of absolute nothingness (except for some colored square panels that do nothing but disappear when one tries to move them). It only appears in "SB-129", where Squidward visits it on accident. After he is chased out of the past by Primitive Sponge and Primitive Star, the time machine goes haywire after he accidentally breaks its switch in his attempt to go home, and it transports him to this white wasteland of loneliness.
At a first glance, there appears to be nothing in this dimension, but walking down a bit further reveals some different colored square panels on the "floor" and "ceiling" of the dimension. There are also some strange voices that can be heard and every sound made is echoed, that also includes The Alone Group echoing "alone" in a rather disturbing way.
Nowhere seems to be absolutely nothing, nothing physical, no trace of life, just plain emptiness that seems to go on forever so it can be assumed that absolutely nothing or nobody is here because it is either the end of time or before time.
When Squidward first enters here, he seems to be the only thing visible in this lonely place. As he walks along further, he finds square tiles that he can lift up (which then float up and then disappear after doing so). After summing up that SpongeBob and Patrick are nowhere within sight, he relishes the fact that he found a place where he can be all to himself and with nobody else around.
However, after he hears many voices echo "Alone," he becomes frightened. He then attempts to get out of the terrifying nothingness by running, hoping to find its edge or some sort of existing barrier. However, Squidward keeps looping right back to his starting point, implying that there is nowhere to go in this realm but into infinite nothingness in all directions. (Squidward, however, doesn't seem to be aware of the fact that he is looping). After looping back four times, Squidward notices the time machine, and really nothing else, is anywhere to be found.
After stomping the floor, four times, he finds the time machine again after falling through its ceiling. Squidward then finally breaks down, begs to go home, and admits he misses his home, his Easter Island monument, and his neighbor SpongeBob. After he speaks the final sentence, Squidward is finally able to escape the realm.
The name of this location is given by Squidward when he says "I-I-I was in space, a-and I went to the future, and-and then I went to the past, and-and then-then I was nowhere, but now I'm back, and-and... you don't know how happy I am to see you guys."
In the background, there is a pink panel and a yellow panel, both on the ceiling. They may be meant to resemble SpongeBob and Patrick.
There is an error during the scene where Squidward first arrives at "Nowhere." When he discovers the colored panels, he tries to lift up the cyan-colored one before it floats up and disappears. However, when the scene zooms in (actually out on Squidward himself), this same panel re-appears for a few moments in the same place it was before.
The panel is also a slightly different color shade than the first time.
Nowhere seems breathable for creatures who normally need water in order to breathe, and Squidward is an obvious example. In Nowhere, there doesn't seem to be any water at all.
It's unknown how the physics here work, as when he runs far away in search above his time machine when he realizes it disappeared, Squidward ends up in the same place he started and is apparently above the time machine the whole time.