Learn Dutch: Dit kasteel heeft veel obstakels, waaronder een heel brede gracht. - This castle has many obstacles, including a very wide moat.

In Dutch, the relative pronominal adverb waaronder (waar + onder) is the standard way to say "among which" or "including" when giving examples from a larger, previously mentioned group (here, the obstakels). You can think of it as the specific examples falling "under" the umbrella of that broader category.

Could I use inclusief instead of waaronder in this sentence?

While inclusief means "including", it sounds less natural here. Inclusief is typically used when things are packaged together or financially included (like "tax included" or "breakfast included"). When singling out examples from a category, waaronder is much more common and idiomatic.

Why is it heel brede gracht and not hele brede gracht?

Here, heel functions as an adverb meaning "very", modifying the adjective brede (wide). Adverbs don't take an -e ending. You will often hear native speakers say een hele brede gracht in casual speech, but standard written Dutch requires the uninflected heel.

Why does breed get an -e ending (brede) if it comes after the indefinite article een?