Word meaning the opposite of "negligible"?

"Negligible" roughly means "Small enough to essentially be zero." For example, in high school physics problems, air resistance is negligible. Is there a word that means "large enough to be essentially infinite"? For example, "For someone on a bike, the distance to the other side of the world is ______."

Solution 1:

Are you looking for "immensurable" or "immeasurable"?

immensurable (adj) immeasurable, impossible to measure TFD

• "He was a man who displayed immensurable courage even in the face of overwhelming adversity."
• "The immensurable magnitude of some stars."
• "Its applicability is immensurable."

Solution 2:

I would say it's substantial.

substantial adj
1. Considerable in importance, value, degree, amount, or extent:

TFD

(Note that you could go with considerable itself as well.)