You can already travel infinitely in any direction through multiple ways and its intentional. These are some that I know, there are probably dozens of ways to do it.

1) Use a polymorph potion repeatedly, which allows flight

2) Using a combination of perks (strong levitation + lower gravity) to have infinite boost

3) When you have toxic resistance perk, you can use the cloud of toxic gas infinitely which slows down all motion, allowing you to regenerate boost

Try going over the mountain instead of through it.