Learn Hardcore Norwegian: Utsikten fra fjelltoppen er den vakreste jeg noen gang har sett. - The view from the mountain top is the most beautiful I have ever seen.

It’s the superlative used predicatively: den + superlative -este = the most X. Since utsikten is common gender, you use den. The whole predicate is therefore den vakreste = the most beautiful (one). Without a following noun, this is the normal way to say it in a predicate.

Base: vakker (beautiful)
Comparative: vakrere (more beautiful)
Superlative: vakrest / den vakreste (most beautiful)
In this context, den vakreste is the idiomatic choice.

You will also see bare predicative superlatives like best: e.g., Det er best. With adjectives like vakker, the form with den is very common when you mean “the most … (of all).”

Could I say mest vakker or den mest vakre instead of den vakreste?

No. For short native adjectives like vakker, Norwegian strongly prefers the suffix forms -ere/-est: vakrere/vakrest, and with definiteness den vakreste. Phrases like mest vakker or, worse, den mest vakreste (double superlative) are non-idiomatic or wrong.

Use mer/mest with many longer or foreign adjectives:

interessant → mer interessant → mest interessant

Why is it den, not det or de?

Agreement:

Common gender singular noun (like utsikten): den vakreste
Neuter singular noun (e.g., huset): det vakreste
Plural (e.g., bildene): de vakreste

Examples:

Huset er det vakreste jeg noen gang har sett.
Bildene er de vakreste jeg noen gang har sett.

What’s going on with the word order in jeg noen gang har sett? Why is noen gang placed there?

This is a subordinate (relative) clause. In Norwegian subordinate clauses, the subject comes before the finite verb, and sentence adverbs (like ikke, aldri, noensinne/noen gang) come right after the subject:

… som jeg aldri/ noensinne/ noen gang har sett

So jeg noen gang har sett is the natural order. The alternative jeg har noen gang sett sounds off. In a main clause you’d say:

Jeg har aldri/noensinne/ noensinne sett … (adverb after the finite verb in main clauses)

Where is the relative word som? Is it missing?

It’s optional here and has been dropped. Full form:

… den vakreste som jeg noen gang har sett.

Norwegian lets you omit som when it is the object of the relative clause (here, it stands for “the thing” that I have seen). You must keep som when it is the subject:

Keep: Mannen som kom …
Optional: Mannen (som) jeg så …

What’s the difference between noen gang, noensinne, and noen ganger?

noen gang and noensinne both mean “ever.” Noensinne is a bit more formal; noen gang is very common in speech. Your sentence works with either: … jeg noensinne/ noen gang har sett.
noen ganger means “sometimes,” which is different in meaning and cannot be used here.

Why is it har sett (present perfect) and not så (preterite)?

Present perfect (har sett) is the default for life experience up to now, just like English “have seen,” especially with ever-type expressions and superlatives. … jeg noen gang så can appear in some dialects or specific past-time contexts, but standard written Bokmål prefers har sett here.

Why is it fra fjelltoppen and not på fjelltoppen?

fra fjelltoppen = the view from the mountaintop (source/origin of the view).
på fjelltoppen = at/on the mountaintop (location). You could say Utsikten på fjelltoppen er flott, but when specifying where the view comes from, fra is the natural preposition.

Why is fjelltoppen written as one word?

Norwegian writes compound nouns as one word. fjelltoppen = fjell (mountain) + topp (top) + -en (definite ending) → “the mountaintop.” Indefinite forms:

en fjelltopp (a mountaintop)
fjelltopper (mountaintops)
fjelltoppene (the mountaintops)

Why is utsikten definite? Could I say En utsikt fra fjelltoppen …?

Norwegian often uses the definite form when the referent is uniquely identifiable in context. “The view from the mountaintop” is a specific, contextually unique thing, so Utsikten is natural. You can use the indefinite (En utsikt …) if you’re introducing it non-specifically, but with superlatives comparing a known, specific view, definiteness feels right.

Shouldn’t it be den vakreste utsikten? Why is the noun missing after the adjective?

In predicative position you normally don’t repeat the noun:

Utsikten … er den vakreste (jeg … har sett).

If you put the adjective before the noun attributively, you must use double definiteness:

Dette er den vakreste utsikten (jeg … har sett). Here you need both den and the definite ending -en on utsikt.

What gender are utsikt and fjelltopp, and does that affect the sentence?

Both are common gender nouns in Bokmål:

en utsikt → utsikten
en fjelltopp → fjelltoppen

This is why the agreeing superlative is den vakreste (not det). In a neuter context you’d have det vakreste.

Is er vakrest also possible instead of er den vakreste?

Grammatically, yes—Norwegian allows bare predicative superlatives (e.g., Det er best). With adjectives like vakker, though, den vakreste is the most idiomatic when you mean “the most … (of all),” especially with … jeg noensinne/ noen gang har sett. Utsikten … er vakrest (av alt/alle) can work if you add an explicit comparison set.

Any quick pronunciation tips for tricky words here?

Utsikten: roughly [OOT-sik-ten] (u like “oo” in “boot,” stress on first syllable).
fjelltoppen: [FYELL-top-pen] (j like English y; stress on first syllable).
vakreste: [VAHK-re-ste] (r is tapped; stress on first syllable).
jeg: varies by dialect; common are [yai] or [jæ].