terminos de geografía.

Hi !!
I have some doubts about the exact translation of these terms. Could you help me¿

cerro = hill ?

serranía = mountain ? (I think montaña is mountain, but then which word is best for SERRANÍA?)

and then, which is the correct translation for "sucesión de cerros"?

successive hills or a succession of hills?

I write the context below so you can see it better.
thanks a lot !!

context:
De suelo suavemente ondulado, una sucesión de cerros y serranías así como kilómetros de playas sobre el Río de la Plata y el Atlántico conforman un paisaje inolvidable por su gran belleza natural.

my translation is the following:
Gently undulated ground, successive hills and mountainous area as well as kilometers of beaches along the River Plate and the Atlantic Ocean, constitute an unforgettable landscape for its natural beauty.

cerro = hill
serranía = mountains, mountain range, hilly country

Hello,

Your translation is very good. I would change a few things in the translation though. Is this aimed at a U.S. audience? If so, I would use miles instead of kilometers. Here's your translation with a few corrections :)

Gently undulated ground, a succession of hills and mountains, as well as miles of beaches along the River Plate and the Atlantic Ocean, constitute an unforgettable landscape through its natural beauty.

I hope this helps :)