De or het diepboring?

The correct Dutch article is:

de diepboring

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

How to use diepboring

the diepboringde diepboring
this diepboringdeze diepboring
that diepboringdie diepboring
our diepboringonze diepboring
your diepboringjouw diepboring
every diepboringelke diepboring
which diepboring?welke diepboring?
a big diepboring / the big diepboringeen grote diepboring, de grote diepboring