Surface

The Surface is the region of the Earth that humans live on. It is where the main character and all Eight Humans that have fallen into the Underground have come from. The Surface is separated from the Underground by the Barrier.

The only portions of the Surface that have been witnessed are a large cliff extended over a forested region, a city, and Mount Ebott, which is the only known way to pass from the Surface to the Underground.

Mount Ebott
A mountain on the Surface of the Earth, it is currently the only known point of entry into the Underground. So far, Eight Humans have fallen through Mt. Ebott's Barrier into the Underground. Is it depicted at the beginning of Undertale's intro.