Learn Swedish: Vad finns inuti den mörka containern? - What is inside the dark container?

In Swedish, the passive verb finns (literally "is found") is the natural way to express existence or presence, much like "is there" or "are there" in English. When asking what exists in a location, finns is the standard choice. If you used är, it would sound like you are trying to identify a specific, already-known object rather than asking what happens to be located inside.

Could I just use i instead of inuti here?

Yes, you could simply say i (in), but inuti specifically emphasizes the physical interior ("inside of" or "within"). It draws attention to the fact that the object is enclosed, which perfectly fits the slightly mysterious tone of a "dark container."

Why do we need the word den if the noun is already definite (containern)?

This is a classic feature of Swedish called "double definiteness." When a definite noun (like containern) is modified by an adjective (like mörka), you must also add the freestanding definite article (den, det, or de) before the adjective. You are essentially saying "the dark container-the."

Container is an English loanword. How does it fit into Swedish noun patterns?