De or het skihelling?

The correct Dutch article is:

de skihelling

Rule Words ending in -ing: almost always de. See the rule

How to use skihelling

the skihellingde skihelling
this skihellingdeze skihelling
that skihellingdie skihelling
our skihellingonze skihelling
your skihellingjouw skihelling
every skihellingelke skihelling
which skihelling?welke skihelling?
a big skihelling / the big skihellingeen grote skihelling, de grote skihelling