Við stoppum aftur við klettinn, því hún vill dást að fossinum einu sinni enn.

They are two different words that just happen to be spelled the same:

• Við at the beginning = the pronoun we
• við later in the sentence = a preposition meaning by, at, near, or sometimes against, depending on context

So Við stoppum ... við klettinn means We stop ... by the rock/cliff.

Yes. The verb stoppa is a normal Icelandic verb, and it is clearly related to stop.

Here, stoppum is:

• present tense
• 1st person plural
• so it means we stop or we are stopping

The ending -um is the important part here: it shows we.

Because klettinn is not the basic dictionary form.

• klettur = rock / cliff in the nominative singular, indefinite
• klettinn = the rock / the cliff in the accusative singular, definite

Two things are happening:

1. The noun is definite: Icelandic usually adds the onto the end of the noun instead of using a separate word.
2. The preposition við takes the accusative, so the noun changes form.

So við klettinn means by the rock/cliff.

Fossinum is dative singular definite of foss.

That form appears because of the verb phrase dást að, which requires:

• að
• followed by a noun in the dative

So:

• foss = waterfall
• fossi = waterfall in the dative singular
• fossinum = the waterfall in the dative singular

This is something learners need to memorize with the verb: dást að einhverju = admire something.

Because dást is one of those Icelandic verbs that comes with a fixed preposition.

You do not just memorize dást by itself; you memorize:

• dást að e-u = to admire / marvel at something

This is similar to how English verbs sometimes need fixed partners, like listen to or look at. In Icelandic, these combinations often also control a specific case.

So here:

• dást að fossinum = admire the waterfall

Here því means because.

It introduces the reason clause:

• því hún vill dást að fossinum ... = because she wants to admire the waterfall ...

You may also see því að with the same meaning. In many sentences, því by itself is enough.

Because því here is a subordinating conjunction meaning because.

In a subordinate clause, Icelandic often keeps a more regular order:

• hún vill ... = she wants ...

Main clauses in Icelandic usually follow the verb-second pattern, but subordinate clauses introduced by words like því do not behave the same way.

So því hún vill dást ... is the expected structure.

Because after vilja and other modal-type verbs, Icelandic normally uses a bare infinitive.

So:

• hún vill dást = she wants to admire

There is no infinitive marker að after vill here.

This is similar to English:

• she wants to admire
• but after modals in English we say she can admire, not she can to admire

Icelandic has its own pattern, and with vilja, the infinitive comes directly after it.

No. Even though they look similar, vill here is from the verb vilja, meaning to want.

So:

• hún vill dást = she wants to admire

It is not a future marker here. Icelandic usually does not form the future with vilja the way English uses will.

Yes, both express repetition, but they apply to different parts of the sentence.

• aftur goes with stoppum: we stop again
• einu sinni enn goes with dást: to admire ... once more

So the sentence is saying:

• the stopping happens again
• and the admiring happens one more time

That is not redundant; it is actually quite natural.

It means once more, one more time, or yet again, depending on context.

A helpful way to understand it is:

• einu sinni = once
• enn = still / yet / more, depending on context

Together, einu sinni enn means once again or one more time.

All of those are possible depending on the situation.

The preposition við often has a general sense of being by, at, or next to something. With a place noun, English translation depends on what sounds most natural.

So við klettinn could be understood as:

• by the rock
• at the cliff
• near the crag

Also, klettur can mean anything from a large rock to a crag or cliff, depending on context.

Because Icelandic often uses commas before subordinate clauses more readily than modern English does.

Since því hún vill dást að fossinum ... is a subordinate clause giving the reason, the comma is normal Icelandic punctuation here.