Learn Hardcore Indonesian: Di aula museum ada film tentang paus dan lumba-lumba yang berenang di laut dalam. - In the museum hall there is a film about whales and dolphins swimming in the deep sea.

di aula museum is shorter and very natural; it already implies “in/at the hall”.
di dalam aula museum emphasizes the interior more strongly (literally “inside the museum hall”), which you might use if you contrast inside vs outside.

In everyday speech, di aula museum is usually enough.

Why is it aula museum and not aula di museum or aula dari museum?

In Indonesian, placing two nouns side by side often shows possession or a close relationship, similar to English “museum hall” or “school library”:

aula museum = the hall of the museum / the museum hall
perpustakaan sekolah = the school library

You could say:

aula di museum = “the hall that is at the museum”
(grammatically OK, but sounds slightly more descriptive, less like a fixed label)
aula dari museum is less natural here; dari usually means “from” and is not the usual way to express possession for places.

So aula museum is the most natural way to say “the museum’s hall / the museum hall.”

What does ada do in this sentence, and how is it different from adalah or punya?

Here, ada functions as an existential verb, meaning “there is / there are”:

Di aula museum ada film…
= In the museum hall, there is a film…

Differences:

ada
- Main uses:
  - “there is / there are”:
    Ada buku di meja. – There is a book on the table.
  - “to exist / to be present”:
    Dia ada di rumah. – He/She is at home.
adalah
- Works like “is/are” in definitions/equations:
  Jakarta adalah ibu kota Indonesia. – Jakarta is the capital of Indonesia.
- You do not use adalah just to say “there is/there are”.
punya
- Means “to have / to own”:
  Saya punya buku. – I have a book.

So for “there is a film…”, ada is the correct choice.

How would I say “There is a film…” vs “There are films…” in Indonesian? Does film here mean singular or plural?

Indonesian nouns don’t change form for singular or plural. Film can mean “a film” or “films”, depending on context.

Patterns:

There is a film…
- Ada film tentang paus dan lumba-lumba…
- Or more explicitly singular:
  Ada sebuah film tentang paus dan lumba-lumba…
  (sebuah = one (unit) for objects)
There are films…
- Ada film-film tentang paus dan lumba-lumba…
  (repeating the noun film-film often indicates plural)
- Or: Ada beberapa film… – There are several films…

In your sentence ada film tentang paus dan lumba-lumba…, without extra context it’s usually understood as “there is a film…” (singular), but it could be plural if the broader context makes that clear.

What does tentang mean, and how is it different from words like mengenai?

Tentang means “about / regarding / on the topic of”.

film tentang paus dan lumba-lumba
= a film about whales and dolphins

You could also say:

film mengenai paus dan lumba-lumba
film tentang paus dan lumba-lumba

Differences:

tentang is very common, neutral, and works in spoken and written Indonesian.
mengenai is also common but sounds a bit more formal or bookish, often seen in documents, articles, etc.

In everyday speech, tentang is usually the most natural choice.

Does yang berenang di laut dalam describe both paus and lumba-lumba, or only lumba-lumba?

In Indonesian, when you have A dan B yang …, the yang-clause normally describes both A and B, unless context says otherwise.

So in:

paus dan lumba-lumba yang berenang di laut dalam

yang berenang di laut dalam is understood to describe both whales and dolphins:

“…whales and dolphins that swim in the deep sea.”

If you wanted to say it describes only lumba-lumba, you would usually rephrase more clearly, for example:

paus dan lumba-lumba, dan lumba-lumba itu berenang di laut dalam
(two separate clauses), or
paus dan lumba-lumba yang (khususnya) lumba-lumba itu berenang di laut dalam
(but this starts to sound awkward; better to use separate sentences).

So as written, it naturally includes both animals.

What exactly is yang doing here, and when do I use it?

Yang introduces a relative clause or highlights something being described.

In your sentence:

paus dan lumba-lumba yang berenang di laut dalam
= “whales and dolphins that swim in the deep sea”

Structure:

[noun] + yang + [description / clause]

Examples:

orang yang memakai baju merah
= “the person who is wearing a red shirt”
film yang menarik
= “a film that is interesting”

So yang is like “that / who / which” (but doesn’t change form for gender or number) and marks the start of a descriptive clause modifying the noun.

Why is it laut dalam and not dalam laut for “deep sea”? Where do adjectives go?

In Indonesian, adjectives usually come after the noun they describe.

laut dalam
= laut (sea) + dalam (deep)
= “deep sea”
buku tebal
= “thick book”
kota besar
= “big city”

So:

laut dalam = “deep sea”
laut yang dalam = “sea that is deep” (more explicitly descriptive, but similar meaning)

Dalam laut (reversed) would normally be read as “inside the sea” (preposition dalam = “inside”), not “deep sea”. So laut dalam is the correct order for the noun phrase “deep sea”.

Could I say laut yang dalam instead of laut dalam? Is there any difference?

Yes, you can say both:

laut dalam – “deep sea”
laut yang dalam – “sea that is deep”

Differences in feel:

laut dalam is a concise noun + adjective phrase, like a standard label or description.
laut yang dalam sounds a bit more explicit or emphatic, as if you’re really stressing that the sea is deep, or describing a particular sea in context.

In your sentence, berenang di laut dalam is very natural and standard. berenang di laut yang dalam is also correct but a bit more verbose.

How do we know the tense? Could it mean “was a film” or “will be a film”?

Indonesian usually does not mark tense with verb changes. Instead, you understand tense from context or from time words.

Your sentence:

Di aula museum ada film tentang…

Without extra context, it most naturally reads as present:
“In the museum hall, there is a film about…”

To show time more clearly, you add time expressions:

Tadi di aula museum ada film… – Earlier, there was a film… (past)
Besok di aula museum ada film… – Tomorrow, there will be a film… (future)
Kemarin di aula museum ada film… – Yesterday, there was a film…

The verb ada itself does not change form for past/present/future.

Does berenang mean “are swimming” or “to swim”? Why is there ber- at the beginning?

Berenang comes from the root renang (swimming) plus the prefix ber-, which often forms intransitive verbs (no direct object).

berenang = “to swim” / “swimming” / “(are) swimming”

In Indonesian, verb forms don’t change for tense or aspect, so:

Paulus berenang di laut.
Could be “Paul swims in the sea,” “Paul is swimming in the sea,” or “Paul swam in the sea,” depending on context.

In your sentence:

paus dan lumba-lumba yang berenang di laut dalam
= “whales and dolphins that swim / that are swimming in the deep sea”

The ber- prefix here just turns the root into a verb meaning “to do that activity” (swim).

Is the sentence Di aula museum ada film tentang paus dan lumba-lumba yang berenang di laut dalam natural Indonesian? In what context would it be used?

Yes, it is natural and clear Indonesian.

It would fit in contexts like:

Informing someone about what’s being shown at a museum:
“In the museum hall there is a film about whales and dolphins that swim in the deep sea.”
A written description in a brochure, guide, or announcement.

If you wanted a bit more formal or specific style, you could also see variants like:

Di aula museum sedang diputar film tentang paus dan lumba-lumba…
= “In the museum hall, a film about whales and dolphins is being shown…”

But your original sentence is already correct, natural, and easy to understand.