Jag längtar efter sommaren, för då badar jag i havet.

In Swedish, the verb längta usually takes the preposition efter when you say what you are longing for.

• jag längtar efter sommaren = I long for / I’m looking forward to the summer

So efter is part of the normal pattern of the verb here, much like English long for.

A few examples:

• Hon längtar efter semestern. = She is looking forward to the vacation.
• Vi längtar efter dig. = We miss / long for you.

Sommaren is the definite singular form of sommar.

• en sommar = a summer
• sommaren = the summer

In Swedish, the definite article is often added to the end of the noun, instead of being a separate word like English the.

Here, sommaren is natural because it refers to the summer season in a general, familiar sense: the coming summer / summer as a known time of year.

In this sentence, för works as a conjunction meaning because or for.

• Jag längtar efter sommaren, för då badar jag i havet.
• I’m looking forward to the summer, because then I swim in the sea.

This för connects two full clauses.

Do not confuse it with för in other uses, such as:

• för stor = too big
• en present för dig = a present for you

So Swedish för has several meanings depending on context.

Here, då means then or at that time.

So:

• för då badar jag i havet = because then I swim in the sea

It refers back to sommaren. In other words, during that time / in summer, I swim in the sea.

This is because Swedish follows the V2 rule in main clauses: the finite verb usually comes in the second position.

When då comes first, the verb must come next:

• Då badar jag i havet.

Not:

• Då jag badar i havet — this would not work as a normal main clause here.

Compare:

• Jag badar i havet då.
• Då badar jag i havet.

Both are possible, but when då starts the clause, badar must come before jag.

Swedish often uses the present tense for things that are:

• habitual
• generally true
• regularly repeated
• sometimes even future, if the context makes the time clear

So då badar jag i havet means something like:

• then I swim in the sea
• that’s when I swim in the sea
• I swim in the sea then / in summer

It describes a habit or repeated action, not necessarily something happening right this moment.

It can mean either, depending on context.

The verb bada often refers to being in the water for pleasure, so in English it may be translated as:

• swim
• go swimming
• bathe

In this sentence, badar jag i havet most naturally means I swim / go swimming in the sea.

So Swedish bada is a bit broader than English bathe.

Because if you are swimming, you are in the water, so Swedish uses i.

• i havet = in the sea

Compare:

• Jag badar i havet. = I swim in the sea.
• Jag är på havet. = I am on the sea / out at sea

So i is used for being inside the water, while på would suggest being on the surface or out at sea, for example in a boat.

Havet is the definite form of hav:

• ett hav = a sea
• havet = the sea

In Swedish, definite forms are often used where English also uses the. Here, i havet means in the sea, referring to the sea as a known natural place.

It would sound less natural here to say just i hav.

The comma before för helps separate the two clauses:

• Jag längtar efter sommaren
• för då badar jag i havet

In Swedish, punctuation can be a little flexible, but this comma is perfectly normal and makes the sentence easier to read.

Even without focusing on punctuation, the grammar stays the same:

• för introduces the reason
• då badar jag keeps normal main-clause word order after fronting då

Yes, depending on context, längta efter can express either:

• longing for something in the future
• missing something that is absent

So jag längtar efter sommaren could mean:

• I’m looking forward to the summer
• I long for summer
• sometimes even I miss summer

In this sentence, because of för då badar jag i havet, the intended meaning is most likely I’m looking forward to the summer, since the speaker is talking about what happens then.