Al atardecer, me gusta sentarme en un banco del paseo y mirar el mar.

Al atardecer means at dusk / at sunset / in the evening as it gets dark.

Here, al is the contraction of a + el:

• a el atardecer → al atardecer

In this kind of time expression, al + infinitive/noun can mean when or at the time of. In this sentence, it works like a set expression meaning at dusk.

Similar examples:

• al amanecer = at dawn
• al anochecer = at nightfall

So Al atardecer is a very natural way to begin the sentence.

Because gustar works differently from to like in English.

Spanish structures it more like:

• me gusta sentarme... = sitting down... is pleasing to me

So:

• me = to me
• gusta = is pleasing

That is why Spanish says:

• Me gusta el mar = I like the sea
• literally: The sea pleases me

Using yo gusto would usually mean I am pleasing / attractive, which is a completely different meaning.

Because the thing that is pleasing here is the whole action:

• sentarme en un banco del paseo y mirar el mar

When gustar is followed by an infinitive, the infinitive phrase counts as a singular idea, so Spanish uses gusta, not gustan.

Compare:

• Me gusta nadar. = I like swimming.
• Me gustan los libros. = I like books.

So in your sentence, the liked thing is to sit down on a bench... and look at the sea, which is treated as one singular activity.

Because the verb here is sentarse, not just sentar.

• sentar usually means to seat someone / to sit something down
• sentarse means to sit down / to seat oneself

So:

• Me gusta sentarme = I like to sit down
• Me gusta sentar a mi hijo = I like to seat my son (very different meaning)

The me attached to sentar is the reflexive pronoun, making it sentarme.

In Spanish, when you use a reflexive verb in the infinitive, the pronoun can be attached to the end:

• sentarme
• levantarme
• dormirme

Since gustar is already conjugated (me gusta), the next verb stays in the infinitive, and the reflexive pronoun attaches to it:

• me gusta sentarme
• me gusta levantarme temprano

This is normal and required here.

No. Me gusta me sentar is incorrect.

With an infinitive, the reflexive pronoun must go with that infinitive:

• me gusta sentarme ✅

With a conjugated reflexive verb, the pronoun goes before the verb:

• me siento ✅ = I sit down / I am sitting down

So:

• Me gusta sentarme = correct
• Me gusta me sentar = incorrect

Here, banco means bench, not bank.

Spanish banco can mean both:

• bank (the place with money)
• bench

In this sentence, because we are talking about the promenade and the sea, it clearly means a bench.

Del is the contraction of de + el:

• de el paseo → del paseo

So un banco del paseo literally means a bench of the promenade.

In more natural English, that would usually be:

• a bench on the promenade
• a bench along the seafront promenade

Spanish often uses de where English would prefer on, in, or along depending on context.

In Spain, paseo often refers to a promenade, walk, or broad walkway, especially one by the sea or in a pleasant public area.

So in this sentence, el paseo is very likely:

• a seafront promenade
• a walkway by the sea
• a place where people stroll

It does not just mean the action a walk here; it refers to the actual place.

Because they work differently.

In al atardecer, atardecer is part of a fixed time expression meaning at dusk. It behaves more like a set phrase.

But el mar is a noun meaning the sea, and Spanish often uses the definite article with nouns where English may or may not.

So:

• al atardecer = at dusk
• el mar = the sea

Both are completely natural in Spanish.

Both mirar and ver relate to sight, but they are not the same.

• ver = to see
• mirar = to look at

Here the person is intentionally sitting and watching the sea, so mirar fits better.

Compare:

• Veo el mar desde mi ventana. = I see the sea from my window.
• Me gusta mirar el mar. = I like looking at the sea.

So mirar emphasizes the deliberate act of looking.

Spanish often uses the definite article with nouns in a general or familiar sense.

So mirar el mar is the normal way to say to look at the sea.

This is similar to:

• escuchar la música = to listen to music
• mirar el cielo = to look at the sky

In English, we sometimes drop the article, but in Spanish it is often kept.

Because Spanish often leaves out subject pronouns when they are already clear from the context or the verb structure.

In this sentence, yo is understood from me gusta.

So:

• (Yo) me gusta sentarme... would sound wrong anyway, because gustar does not work like a normal I like verb.
• The natural form is simply Me gusta sentarme...

Spanish is a pro-drop language, so omitting the subject pronoun is very common.

Because both actions are things the speaker likes doing:

• sentarme en un banco del paseo
• mirar el mar

After me gusta, Spanish can list one or more infinitive actions:

• Me gusta leer y escribir.
• Me gusta pasear y escuchar música.

So here:

• me gusta sentarme... y mirar el mar means
• I like to sit down... and look at the sea

Because the verbs themselves are different.

• sentarse is reflexive
• mirar is not reflexive

So when they appear in the infinitive:

• sentarme = to sit down
• mirar = to look at

You only add a reflexive pronoun when the verb actually requires it.

More precisely, sentarse means to sit down.

That said, in natural English, I like sitting on a bench... may sound more idiomatic than I like to sit down on a bench..., depending on context.

So grammatically:

• sentarse = to sit down

But in smooth English translation, it may become:

• I like sitting on a bench...

Yes, but it would change the nuance.

• sentarme focuses on the action of sitting down / placing oneself there
• estar sentado focuses on the state of being seated

Compare:

• Me gusta sentarme en un banco... = I like to sit down on a bench...
• Me gusta estar sentado en un banco... = I like being seated on a bench...

Both are possible, but the original sentence sounds very natural and slightly more active.

Because Al atardecer is an introductory time phrase.

In Spanish, a comma after a short introductory phrase is often optional, but it is very common and helps readability.

So:

• Al atardecer, me gusta... ✅
• Al atardecer me gusta... ✅

Both are acceptable. The version with the comma simply marks the opening phrase more clearly.

Yes, it sounds very natural in Spain, especially because of paseo in the sense of a promenade by the sea.

The whole sentence has a very Mediterranean, coastal-Spain feel:

• al atardecer
• un banco del paseo
• mirar el mar

It would be understood everywhere in the Spanish-speaking world, but the word paseo in this setting feels especially familiar in Spain.