Na obali smo vidjeli malu meduzu blizu stijena.

Because na can take different cases depending on meaning:

• na + locative = location, on/at
• na + accusative = motion toward, onto/to

Here, na obali means on the shore / at the shore, so it uses the locative singular of obala:

• obala = shore, coast
• na obali = on/at the shore

Compare:

• Na obali smo bili. = We were on the shore.
• Išli smo na obalu. = We went to the shore.

So na obali is correct because the sentence describes where we saw something, not movement toward the shore.

Croatian past tense is usually made with:

• a present-tense form of biti (to be)
• plus the l-participle of the main verb

Here:

• smo = we are (auxiliary form used in the past tense)
• vidjeli = past participle of vidjeti (to see)

So:

• smo vidjeli = we saw / we have seen

This is the normal way to say the past in Croatian.

Both are possible, but Croatian has a strong tendency for short unstressed words like smo to go in second position in the clause.

In this sentence:

• Na obali = first unit
• smo = second-position clitic
• vidjeli = follows after that

So Na obali smo vidjeli... sounds very natural.

You can also hear vidjeli smo in other sentence structures, for example:

• Vidjeli smo malu meduzu. = We saw a small jellyfish.

But after an opening phrase like Na obali, putting smo right after it is the standard pattern.

Because it agrees with the implied subject we.

The participle changes for gender and number:

• vidio = he saw
• vidjela = she saw
• vidjeli = they saw / we saw (masculine or mixed group)
• vidjele = they saw / we saw (all-female group)

So smo vidjeli means we saw if the speakers are:

• all male, or
• a mixed group, or
• unspecified in many general contexts

If the speakers were all female, you would say:

• Na obali smo vidjele malu meduzu blizu stijena.

Because Croatian usually leaves subject pronouns out when they are already clear from the verb form.

Here, smo already tells you the subject is we.

So:

• Na obali smo vidjeli... = We saw...
• Mi smo vidjeli... = We saw... (with extra emphasis, contrast, or clarification)

Croatian often omits pronouns unless they are needed for stress or contrast.

Because both the adjective and the noun must agree in:

• gender
• number
• case

The base forms are:

• mala = small
• meduza = jellyfish

As the direct object of vidjeti, the phrase must be in the accusative singular.

So:

• mala meduza → nominative
• malu meduzu → accusative

That is why both words change.

The dictionary form is meduza.

In the sentence, it appears as meduzu because it is in the accusative singular.

So:

• meduza = jellyfish
• vidjeli smo meduzu = we saw a jellyfish

This is a very common pattern for feminine nouns ending in -a:

• nominative singular: -a
• accusative singular: -u

Blizu normally takes the genitive.

So in:

• blizu stijena = near the rocks

the noun stijena is in the genitive plural.

Important detail:

• dictionary form: stijena = rock, cliff
• genitive singular: stijene
• genitive plural: stijena

So the form stijena here is not nominative singular. It is genitive plural after blizu.

In this sentence, it works like a preposition-like word meaning near, and it is followed by the genitive:

• blizu stijena = near the rocks

You can also see blizu used more adverbially in other contexts, meaning nearby or close.

But in this sentence, the important thing for a learner is:

• blizu + genitive

Because Croatian has no articles like English a/an/the.

So malu meduzu can mean:

• a small jellyfish
• the small jellyfish

The exact meaning depends on context.

Croatian expresses definiteness in other ways, such as:

• context
• word order
• demonstratives like ta, ova, ona

For example:

• vidjeli smo malu meduzu = we saw a/the small jellyfish
• vidjeli smo tu malu meduzu = we saw that small jellyfish

Yes. Croatian word order is more flexible than English word order.

This sentence is a natural neutral version:

• Na obali smo vidjeli malu meduzu blizu stijena.

But other orders are possible, depending on emphasis:

• Malu meduzu smo vidjeli na obali, blizu stijena.
• Blizu stijena smo na obali vidjeli malu meduzu.

However, one thing usually stays true: the clitic smo tends to appear in second position.

So word order can move around, but not completely freely.

Because vidjeti means to see, not to look/watch.

In this sentence, the idea is that we saw/noticed the jellyfish. That is why vidjeti is the right choice.

Compare:

• vidjeti = to see
• gledati = to look at, watch

So:

• Vidjeli smo malu meduzu. = We saw a small jellyfish.
• Gledali smo malu meduzu. = We were looking at / watching a small jellyfish.

English learners often mix these up, so this is a useful distinction.

It can mean either, depending on context.

• stijena often means a large rock, rocky formation, or cliff/rock face
• in blizu stijena, it most naturally means near the rocks

Croatian words sometimes cover a wider range than a single English word, so context helps you choose the best translation.