De or het zomercompetitie?

The correct Dutch article is:

de zomercompetitie

Rule Words ending in -tie and -sie: almost always de. See the rule

How to use zomercompetitie

the zomercompetitiede zomercompetitie
this zomercompetitiedeze zomercompetitie
that zomercompetitiedie zomercompetitie
our zomercompetitieonze zomercompetitie
your zomercompetitiejouw zomercompetitie
every zomercompetitieelke zomercompetitie
which zomercompetitie?welke zomercompetitie?
a big zomercompetitie / the big zomercompetitieeen grote zomercompetitie, de grote zomercompetitie