Antes del embarque, tenemos que pasar por la aduana.

Because del is the mandatory contraction of de + el.

• de + el = del
• So antes del embarque literally comes from antes de el embarque, but Spanish normally contracts it to del.

This only happens with el, not with la:

• antes del vuelo
• antes de la salida

One important exception: if el is part of a proper name, the contraction is usually not made, for example de El Escorial.

Antes is normally followed by de when it comes before a noun or an infinitive.

So:

• antes de + noun
• antes de + infinitive

In this sentence:

• antes del embarque = antes de + el embarque

Examples:

• antes del vuelo
• antes de salir
• antes de la comida

If you just say antes by itself, it usually means before/earlier in a more general sense:

• Llegué antes. = I arrived earlier.

Here embarque means boarding, especially in an airport or travel context.

So antes del embarque means before boarding.

A few notes:

• In travel Spanish, embarque is very common for boarding a plane, ferry, etc.
• You may also see puerta de embarque = boarding gate
• In other contexts, embarque can also relate to shipment or loading, depending on the situation.

In this sentence, the airport meaning is the natural one.

Tener que + infinitive expresses obligation or necessity: to have to.

So:

• tenemos que pasar = we have to go through / we have to pass through

If you said pasamos, that would usually mean:

• we go through
• we pass through
• or we passed through, depending on context

That would describe an action, not the obligation.

Compare:

• Tenemos que pasar por la aduana. = We have to go through customs.
• Pasamos por la aduana. = We go through customs / We went through customs.

Yes, you could, but the tone changes slightly.

• tenemos que pasar = we have to pass through
• debemos pasar = we must / should pass through

In many contexts, tener que sounds more natural for practical necessity:

• Tenemos que facturar.
• Tenemos que pasar por seguridad.

Debemos can sound a bit more formal, more like a rule, duty, or recommendation depending on context.

For an airport situation, tenemos que pasar por la aduana is very natural.

Because pasar por is the normal expression for to go through a place, process, or checkpoint.

So:

• pasar por la aduana = to go through customs
• pasar por seguridad = to go through security
• pasar por el control = to go through the checkpoint/control

The preposition por often suggests movement through or via something.

This is just the standard Spanish expression; it is not translated word-for-word from English.

Because here customs in English corresponds to singular la aduana in Spanish.

This is a very common difference between the two languages:

• English: customs
• Spanish: la aduana

So even though English uses a plural-looking word, Spanish uses a singular noun.

Examples:

• Tenemos que pasar por la aduana.
• La aduana está cerrada.

You can use aduanas in other contexts if you are talking about customs offices in general or several different customs authorities, but for the checkpoint/process in travel, la aduana is the normal form.

Because Spanish often omits subject pronouns when the verb already makes the subject clear.

• tenemos already tells you the subject is we
• So (nosotros) tenemos que pasar por la aduana and tenemos que pasar por la aduana both mean the same thing

Spanish does this very often:

• Tengo hambre. = I’m hungry.
• Vivimos en Madrid. = We live in Madrid.

You would add nosotros only for emphasis, contrast, or clarity:

• Nosotros tenemos que pasar por la aduana, pero ellos no.

The comma separates the introductory time phrase from the main clause.

• Antes del embarque, = Before boarding,
• tenemos que pasar por la aduana. = we have to go through customs.

This comma is common and helps readability. In short sentences, some punctuation choices can vary, but in a sentence like this, the comma is very natural.

Without the comma, the sentence would still usually be understood:

• Antes del embarque tenemos que pasar por la aduana.

But the version with the comma looks cleaner and more standard.

It can be used in other travel contexts too, not only planes.

For example:

• embarque for a ferry
• embarque for a cruise
• sometimes more generally for boarding a form of transport

At airports, it is especially common:

• tarjeta de embarque = boarding pass
• hora de embarque = boarding time
• puerta de embarque = boarding gate

So in this sentence, learners will most likely understand it as an airport context, but the word itself is not limited only to airplanes.

Yes. Both are correct, but they are structured differently.

• antes del embarque = before boarding
• antes de embarcar = before boarding / before we board

The first uses a noun:

• el embarque = the boarding

The second uses an infinitive:

• embarcar = to board

Both are natural. The noun version can sound slightly more official or typical of airport language, while the infinitive version can sound a bit more action-focused.

A simple guide:

• aduana ≈ ah-DWAH-nah
• embarque ≈ em-BAR-keh

A few pronunciation notes for Spain:

• qu in embarque sounds like a hard k
• The r in embarque is a tapped Spanish r, not a strong English r
• The stress is:
  • aduana
  • embarque

In standard Spain pronunciation:

• aduana → /aˈðwana/
• embarque → /emˈbaɾke/

They are different checkpoints.

• seguridad = security screening
• aduana = customs

At an airport, seguridad usually means the check for prohibited items before entering the departure area. Aduana is about goods, declarations, and customs control, often connected with entering a country or transporting items.

So:

• pasar por seguridad = go through security
• pasar por la aduana = go through customs

In real travel, exactly when you go through customs depends on the airport and whether you are arriving or departing, but grammatically the sentence is completely natural.

It can mean different things depending on context, which is why learners often notice it.

Pasar por can mean:

• to go through
• to pass through
• to stop by
• sometimes to pass by

Examples:

• pasar por la aduana = go through customs
• pasar por tu casa = stop by your house
• pasar por el parque = go through / pass by the park

So the exact meaning comes from the situation. With la aduana, the intended meaning is clearly go through customs.