I havnen spørger jeg, om færgen er forsinket, eller om den snart sejler.

No. It is the Danish preposition i, meaning in or at. It is capitalized only because it begins the sentence.

So:

• i havnen = in the harbor / at the harbor
• not the English pronoun I

Because Danish often puts a place or time expression first when the speaker wants to set the scene.

So I havnen means something like:

• At the harbor, I ask...

It gives the location first, which is very natural in Danish.

This is because Danish is a V2 language in main clauses. That means the finite verb usually comes in the second position.

Here, I havnen takes the first position, so the verb spørger must come next:

• I havnen | spørger | jeg

If the sentence started with jeg, then you would get:

• Jeg spørger i havnen...

Both are possible, but they emphasize the sentence differently.

I havnen is the most straightforward standard way to say in the harbor / at the harbor.

A learner should think of i here as the normal choice for being in that place or area.
You may sometimes hear på havnen in real-life Danish, often with a more local or idiomatic sense of down at the harbor area, but i havnen is very standard and safe.

Because Danish usually adds the definite article to the end of the noun.

So:

• havn = harbor
• havnen = the harbor

and

• færge = ferry
• færgen = the ferry

This is one of the most important differences from English.

They are definite because the speaker means a specific harbor and a specific ferry, not just any harbor or any ferry.

In context, this sounds like:

• the harbor we are at
• the ferry we are waiting for or talking about

Danish uses the definite form very naturally when the thing is identifiable from the situation.

Here om means whether or if in the sense of an indirect yes/no question.

So:

• jeg spørger, om færgen er forsinket
  = I ask whether / if the ferry is delayed

This is the normal word after verbs like:

• spørge = ask
• vide = know
• undersøge = investigate
• se = see

when what follows is an indirect yes/no question.

It matches English if only in the whether sense, not in the condition sense.

Use om for indirect questions:

• Jeg ved ikke, om den sejler.
  = I don’t know if/whether it is sailing.

Use hvis for conditions:

• Hvis den sejler snart, skynder vi os.
  = If it sails soon, we’ll hurry.

So in your sentence, om is correct because the speaker is asking about two possibilities, not giving a condition.

Because the sentence contains two coordinated indirect questions:

• om færgen er forsinket
• eller om den snart sejler

Repeating om makes the structure clear and natural. It shows that both parts are separate alternatives being asked about.

In English we often do the same:

• whether the ferry is delayed, or whether it is leaving soon

You may sometimes see om omitted in similar structures, but repeating it is very normal and often the clearest choice.

Because after om, the clause is an embedded question, not a direct question.

Direct question:

• Er færgen forsinket?

Embedded question:

• ... om færgen er forsinket

In Danish, embedded questions do not use the normal question inversion. The subject stays before the verb.

Because once færgen has already been mentioned, Danish naturally replaces it with the pronoun den.

• færgen is a common-gender noun, so the pronoun is den
• if it were a neuter noun, the pronoun would be det

So:

• færgen → den

This works just like English the ferry → it.

After om, the clause is subordinate, so there is no main-clause inversion. The subject den stays before the verb.

The placement of snart is natural here:

• om den snart sejler

This order sounds very idiomatic and keeps the focus on soon.
You may also encounter om den sejler snart in real Danish, but the version in your sentence is very natural and common.

The main thing to notice is this:

• after om, Danish does not switch to direct-question word order

Sejler literally means sails or goes by boat.

With a ferry, this is the normal verb. In context, it can mean something like:

• is sailing
• is leaving by sea
• is departing

So om den snart sejler means the speaker is asking whether the ferry will be going soon.

The commas mark the boundary between the main clause and the subordinate clauses.

Structure:

• I havnen spørger jeg,
• om færgen er forsinket,
• eller om den snart sejler.

In written Danish, commas are commonly used to separate subordinate clauses like those introduced by om. They help show the sentence structure clearly.