We think of Space as being "flat" (e.g., two parallel lines, by definition, never meet) and having three dimensions (height, width and depth). Yet Space is actually curved -- measurably so in large gravitational fields -- and it appears to have significantly more than three dimensions (this part is currently theoretical, but most of the debate seems to center not on whether or not space has more than three dimensions but rather how many more it has).
We find it impossible to conceptualize ultimate limits in space -- e.g., a smallest or largest possible length. What would happen if you cut the former in half or added an inch to the latter? Yet, in fact, such limits do exist (Ref: 1).
Similarly, there is an ultimate speed -- 186,000 miles per second, the speed that light travels in a vacuum. A maximum speed is, in and of itself, counter intuitive. Nonetheless, this is how the Universe operates -- it is no longer theoretical.
References:
1. "The View from the Center of the Universe: Discovering Our Extraordinary Place in the Cosmos" by Joel R. Primack and Nancy Ellen Abrams