Kad je magla gusta, ne vidim dokle ide staza uz vodu.

Yes. Kad means when here.

In this sentence, Kad je magla gusta means When the fog is thick.

A few useful notes:

• kad and kada both mean when
• kad is more common in everyday speech
• kada can sound a bit more formal or emphatic

So:

• Kad je magla gusta... = When the fog is thick...
• Kada je magla gusta... = same meaning

Because the sentence has two clauses:

1. Kad je magla gusta
2. ne vidim dokle ide staza uz vodu

The first clause is a time clause introduced by kad, and in Croatian it is normally separated by a comma from the main clause.

So the structure is:

• Kad je magla gusta, = subordinate clause
• ne vidim... = main clause

This is very similar to English:

• When the fog is thick, I can’t see...

Both are possible, but they do not sound exactly the same.

Here, magla gusta is part of the predicate after je:

• magla = fog
• je = is
• gusta = thick

So this is literally:

• the fog is thick

That is why gusta comes after je.

If you say gusta magla, that is an adjective directly attached to the noun:

• gusta magla = thick fog

Compare:

• Kad je magla gusta... = When the fog is thick...
• Kad je gusta magla... = also possible, more like When there is thick fog...

Because it agrees with magla.

In Croatian, adjectives change form to match the noun in:

• gender
• number
• case

Here:

• magla is feminine singular nominative
• so the adjective must also be feminine singular nominative
• therefore: gusta

Compare:

• gusta magla = thick fog
• gust dim = thick smoke (dim is masculine)
• gusto lišće = thick/dense foliage (lišće is neuter)

Because Croatian usually does not need the subject pronoun when it is already clear from the verb form.

• vidim = I see
• ne vidim = I do not see / I can’t see

The ending -im already shows I.

You could say ja ne vidim, but that adds emphasis, like:

• I can’t see
• I’m not able to see

Normally, just ne vidim is enough.

In Croatian, the negative particle ne is usually written separately from the verb:

• vidim = I see
• ne vidim = I do not see

This is the normal pattern with most verbs.

Examples:

• znam → ne znam
• mogu → ne mogu
• idem → ne idem

So ne vidim is exactly what you should expect.

Here dokle means something like:

• how far
• up to where
• to what point

So ne vidim dokle ide staza means:

• I can’t see how far the path goes
• I can’t see up to where the path continues

Why not the other words?

• gdje = where (location)
• kamo = where to (direction, destination)
• dokle = up to where / as far as what point

Because a path extends over distance, dokle is very natural here: the speaker cannot see the limit or extent of the path.

Yes. Croatian often uses ići (to go) for roads, paths, trails, rivers, lines, and similar things.

So:

• staza ide uz vodu literally = the path goes along the water
• natural English = the path runs along the water

This is a very normal Croatian way to describe the direction or course of something long and continuous.

Similar examples:

• Put ide kroz šumu. = The road goes through the forest.
• Cesta ide do sela. = The road goes as far as the village.
• Rijeka ide prema moru. = The river goes toward the sea.

Because Croatian often uses the present tense for general truths, usual situations, and things that are happening in the scene being described.

Here the sentence means roughly:

• When the fog is thick, I can’t see how far the path goes along the water.

The path’s course is a general fact, so present tense is natural:

• ide = goes

Also, both clauses are in the present because this describes a repeated or typical situation, not one single completed event.

Staza is in the nominative singular because it is the subject of ide.

In the clause:

• dokle ide staza uz vodu

the subject is staza = the path

So:

• staza ide = the path goes / runs

The noun is feminine singular:

• nominative: staza
• genitive: staze
• accusative: stazu

Here it must be staza, because it is doing the action of going.

Here uz means along, by, or next to.

So:

• staza uz vodu = the path along the water
• depending on context, this could be along the river/lake/shore/water

The preposition uz normally takes the accusative case, so voda changes to vodu:

• nominative: voda
• accusative: vodu

That is why it is uz vodu, not uz voda.

Other examples:

• uz cestu = along the road
• uz rijeku = along the river
• uz zid = along the wall

Literally it means water, but in context it can often refer more broadly to a body of water, especially when the exact type is not important.

So staza uz vodu could suggest:

• a path by the water
• a path along the river
• a path next to the lake
• a waterside path

Croatian often leaves this a bit general if the context already makes it clear.

Yes, but the meaning changes slightly.

• ne vidim = I don’t see / I can’t see
• ne mogu vidjeti = I am not able to see

In many contexts they are very close. But:

• ne vidim is simpler and more natural in ordinary description
• ne mogu vidjeti sounds a bit more explicit about inability

So the original sentence sounds very natural and idiomatic.

Not quite.

• dokle asks about the extent/end point: how far / up to where
• kuda asks about the route/way: which way / along what route

So:

• Ne vidim dokle ide staza uz vodu. = I can’t see how far the path goes along the water.
• Ne vidim kuda ide staza uz vodu. = I can’t see where/which way the path goes along the water.

Both are possible, but they focus on different things.

Yes. Croatian word order is flexible, although some versions sound more natural than others.

The original:

• Kad je magla gusta, ne vidim dokle ide staza uz vodu.

is very natural.

You could also hear variations like:

• Kad je magla gusta, dokle ide staza uz vodu ne vidim.
• Ne vidim, kad je magla gusta, dokle ide staza uz vodu.

But these are less neutral or place emphasis differently.

For a learner, the original order is the best model:

• time clause first
• then the main clause
• then the dokle clause

Usually a general or repeated situation.

Because both verbs are in the present tense:

• je = is
• vidim = I see
• ide = goes

the sentence most naturally means something like:

• Whenever the fog is thick, I can’t see how far the path goes along the water.

So it sounds like a habitual experience, not just one single moment. Context could make it specific, but without extra information, the general reading is the most natural.