Við fórum í ferðalag um Ísland í fyrra.

Because fórum is the past-tense form of the verb fara (to go / to travel) that matches við (we).

So:

• fara = infinitive, to go
• við fórum = we went

In this sentence, the action happened in the past, so Icelandic uses the past tense, not the infinitive.

Yes, fórum already tells you the subject is we, because Icelandic verbs change according to person and number.

But Icelandic still usually includes the subject pronoun in normal sentences:

• Við fórum = We went

So unlike in some languages where the pronoun is often dropped, Icelandic commonly keeps it.

Í ferðalag means something like on a trip, on a journey, or travelling.

The noun is:

• ferðalag = trip, journey, travel

With the verb fara, the phrase fara í ferðalag is a natural expression meaning to go on a trip / set off on a journey.

So this is not just a random combination of words; it is a common Icelandic pattern.

Because Icelandic idiom uses fara í ferðalag.

Very often, Icelandic prepositions are just something you have to learn together with the noun or verb phrase. English speakers often want a direct one-to-one match with English prepositions, but that usually does not work.

Here, the natural expression is:

• fara í ferðalag = go on a trip

Even though English uses on, Icelandic uses í.

It is in the accusative singular.

Why? Because í often takes the accusative when it expresses motion toward something or entering a state/activity, and in fara í ferðalag, that is what is happening.

The noun ferðalag is neuter, and for many neuter nouns the nominative and accusative singular look the same, so you do not see a visible ending change here.

Um Ísland means around Iceland or through Iceland.

The preposition um often means:

• around
• about
• through, depending on context

In this sentence, it gives the idea of travelling around the country.

So:

• ferðalag um Ísland = a trip around Iceland

Um takes the accusative, so Ísland is indeed in the accusative here.

But Ísland is a neuter noun, and in the singular its nominative and accusative forms are the same:

• nominative: Ísland
• accusative: Ísland

So the case does change grammatically, but the word itself does not look different.

Í fyrra is a fixed expression meaning last year.

You can think of it as an idiomatic time phrase. Learners usually just memorize it as a whole:

• í fyrra = last year

It does not translate word-for-word very neatly into natural English, so it is best learned as one chunk.

Because they are doing two different jobs:

• í ferðalag = part of the expression go on a trip
• í fyrra = a time expression meaning last year

So even though the same preposition appears twice, the meaning is different in each phrase. This is very common in Icelandic, just as in English one word can have several uses.

Yes, somewhat.

The sentence as written is natural and neutral:

• Við fórum í ferðalag um Ísland í fyrra.

But Icelandic can move elements around for emphasis. For example:

• Í fyrra fórum við í ferðalag um Ísland. = Last year, we went on a trip around Iceland.

When a different element is placed first, Icelandic normally keeps the finite verb in second position. That is an important word-order pattern in Icelandic.

A rough pronunciation guide for English speakers would be:

• Við ≈ vith
• fórum ≈ FOH-rum
• í ≈ ee
• ferðalag ≈ FER-tha-lag
• um ≈ um
• Ísland ≈ EES-lant
• í fyrra ≈ ee FIR-ra

A few useful notes:

• ð in við and ferðalag is like the th in this
• þ does not appear in this sentence, but it would be like th in thing
• í is a long ee sound
• ó is like oh

Exact pronunciation depends on dialect and natural speech, but this will get you close.

Yes, you could, but the meaning changes slightly.

• Við fórum um Ísland í fyrra = We travelled around Iceland last year
• Við fórum í ferðalag um Ísland í fyrra = We went on a trip around Iceland last year

The version with í ferðalag emphasizes that it was a trip or journey. The version without it is a little more direct and simply says that you went/travelled around Iceland.