Adjective placement in "Volábamos sobre increíbles montañas"

In Spanish 11.5 we're given the following translation

Volábamos sobre increíbles montañas.

(We) were flying over incredible mountains.

Normally I would expect it to be montañas increíbles rather than increíbles montañas 

Is there a reason it looks backwards here?

¡Hola mmmatt!

Thanks for your question!

Adjectives do normally come after nouns in Spanish; however, adjectives can also sometimes be placed before nouns to alter their meaning or the impression that they give. (You can find a full explanation on this in Lesson 3.8: “Adjective Tricks and Placement” under the heading “Before or After the Noun: Changes in Meaning,” if you like.) 

In this particular case, the adjective increíble “incredible” is placed before the noun because this makes it sound more emotional. This before-noun placement is actually quite common with adjectives that have an over-the-top or exaggerated meaning (like increíble “incredible”), since the added emotion suits them well. 

All that being said, however, you wouldn't be wrong if you wanted to say las montañas increíbles. The mountains would just sound a little less emotionally incredible!

I hope that this is helpful! Do let me know if you still need any clarification.

Saludos,

Liss