Hvis vinden bliver stærkere langs kysten, vil vi ikke sejle ud mellem de store bølger.

Hvis means if and introduces a condition.

• Hvis vinden bliver stærkere ... = If the wind gets stronger ...

A common comparison is når, which often means when.

• hvis = a condition, something that may or may not happen
• når = something expected or seen as more certain/repeated

So here hvis fits because the sentence is about a possible situation, not a guaranteed one.

Vind is the basic noun: wind.

Danish often uses the definite form where English might simply say the + noun:

• vind = wind
• vinden = the wind

So vinden literally means the wind.

The ending -en shows that vind is a common-gender noun in the definite singular.

Because bliver stærkere means gets stronger / becomes stronger, not just is stronger.

• er stærkere = is stronger
• bliver stærkere = becomes / gets stronger

The sentence is about a change in condition, so bliver is the natural choice.

Stærkere is the comparative form of stærk (strong).

• stærk = strong
• stærkere = stronger
• stærkest = strongest

So:

• vinden bliver stærkere = the wind gets stronger

This is similar to English strong → stronger.

Langs means along and kysten means the coast.

So:

• langs kysten = along the coast

Kyst is the noun coast.

• kyst
• kysten = the coast

This phrase tells you where the wind is getting stronger.

The first part of the sentence is a subordinate clause introduced by hvis:

• Hvis vinden bliver stærkere langs kysten

Then the main clause follows:

• vil vi ikke sejle ud mellem de store bølger

In standard Danish writing, a comma is commonly used to separate these parts. So the comma helps show that the if-clause has ended and the main statement begins.

This is a very important Danish word-order rule.

When a sentence begins with something other than the subject—here, the whole hvis clause comes first—the finite verb of the main clause comes before the subject.

So Danish has:

• Hvis ..., vil vi ...

not:

• Hvis ..., vi vil ...

This is part of the V2 rule in Danish: in main clauses, the finite verb usually comes in the second position.

Compare:

• Vi vil ikke sejle ud ... = We will not sail out ...
• Hvis ..., vil vi ikke sejle ud ... = If ..., we will not sail out ...

In the main clause, the normal order here is:

• vil = finite verb
• vi = subject
• ikke = negation
• sejle = infinitive

So:

• vil vi ikke sejle = will we not sail

This placement is normal in Danish main clauses after inversion.

Compare:

• Vi vil ikke sejle = We will not sail
• Hvis ..., vil vi ikke sejle = If ..., we will not sail

Yes, vil is often used to express the future, similar to will in English.

• vil vi ikke sejle = we will not sail

But Danish does not have a special future verb ending the way some languages do. Instead, it often uses:

• vil
  • infinitive

However, Danish can also use the present tense for future meaning in many situations. Here vil clearly expresses a future result of the condition.

Sejle means to sail.

Ud means out.

Together, sejle ud means to sail out / head out by boat.

This is a common kind of Danish verb + particle combination, similar to English phrasal verbs:

• gå ud = go out
• køre ud = drive out
• sejle ud = sail out

So the ud adds the idea of movement outward, probably from shore or harbor into open water.

Mellem means between / among.

• mellem bølgerne would mean between the waves
• mellem de store bølger means among the big waves / between the big waves

Here the phrase describes the dangerous situation they want to avoid: sailing out where the waves are large.

This is the definite plural with an adjective.

The noun is:

• en bølge = a wave
• bølger = waves

When Danish uses a definite plural noun with an adjective, it often uses:

• de
  • adjective + plural noun

So:

• store bølger = big waves
• de store bølger = the big waves

The adjective stor becomes store in plural/definite contexts.

This is a very common pattern:

• den store båd = the big boat
• de store både = the big boats

Yes, but it would sound a little different.

• mellem de store bølger = among the big waves
• mellem bølgerne = among the waves / between the waves

The version in your sentence emphasizes that they are specifically the big waves. Using de store bølger highlights the size and danger more clearly.

The main clause by itself would be:

• Vi vil ikke sejle ud mellem de store bølger. = We will not sail out among the big waves.

Then you can add the condition in front:

• Hvis vinden bliver stærkere langs kysten, vil vi ikke sejle ud mellem de store bølger.

Seeing the simple main clause first can make the inversion easier to understand.