Tôi mơ về biển.

Yes. Tôi is a common, neutral way to say I in Vietnamese.

A few useful notes:

• It is polite and fairly safe in many situations.
• Vietnamese pronouns depend a lot on relationship, age, and social context.
• In real life, people often use other words instead of tôi, such as mình, em, anh, or chị, depending on who they are talking to.

So in this sentence, tôi is a straightforward learner-friendly subject pronoun.

Mơ means to dream.

In Vietnamese, mơ can refer to:

• dreaming during sleep
• dreaming in a more figurative sense, like imagining or longing for something

Because of that, Tôi mơ về biển can sound a little poetic or slightly open to interpretation unless the context makes it clear.

You may also hear nằm mơ, which more explicitly means to dream while sleeping.

Here, về means something like about.

So mơ về biển means dream about the sea.

This is a very common pattern:

• nghĩ về... = think about...
• nói về... = talk about...
• mơ về... = dream about...

So về links the verb to the topic or object of thought/dream.

Vietnamese usually keeps a straightforward word order:

subject + verb + preposition/object/topic

So here:

• Tôi = subject
• mơ = verb
• về biển = prepositional phrase, about the sea

That makes Tôi mơ về biển a very normal Vietnamese sentence structure.

Usually, Tôi mơ về biển sounds more natural for I dream about the sea.

Without về, Tôi mơ biển sounds incomplete or unnatural in standard usage.

For this meaning, Vietnamese normally wants mơ về + noun/topic.

Not always.

This sentence can mean either:

• a literal dream while sleeping
• a more poetic or emotional dream/daydream about the sea

If you want to make the sleeping meaning clearer, you can say:

• Tôi nằm mơ về biển.

That more specifically suggests an actual dream during sleep.

They are related, but not the same.

• mơ = dream, imagine, dream about
• mơ ước = dream of / aspire to / wish for

So:

• Tôi mơ về biển = I dream about the sea
• Tôi mơ ước được sống gần biển = I dream of living near the sea

If you are talking about hopes and ambitions, mơ ước is often more precise.

Biển usually means sea.

Important distinctions:

• biển = sea
• đại dương = ocean
• bãi biển = beach

So if the sentence uses biển, the focus is on the sea itself, not specifically the sandy beach.

That said, in casual thought or imagery, biển can sometimes evoke the whole seaside scene.

A few pronunciation points:

• mơ: the vowel ơ is not like English o. It is a mid central-ish vowel. Keep your lips fairly relaxed.
• về: has a grave accent, so it uses a falling tone.
• biển: has the hỏi tone, which is a dipping tone in standard northern Vietnamese.

Very roughly:

• mơ = no tone mark, so it has the level tone
• về = falling tone
• biển = dipping tone

Also note:

• biển ends with -n
• iê in biển forms a vowel combination, not two separate syllables

If a learner says the right consonants and vowels but the wrong tones, Vietnamese listeners may misunderstand, so tones matter a lot.

Sometimes, yes, if the subject is already clear from context.

For example, in conversation, someone might simply say:

• Mơ về biển.

This can work if everyone already knows who is speaking about themselves.

But as a full standalone sentence for learners, Tôi mơ về biển is clearer and more complete.

You usually add không before the verb:

• Tôi không mơ về biển.

That is the normal way to negate it.

Pattern:

• tôi + không + verb

So:

• Tôi không nghĩ về biển.
• Tôi không nói về biển.
• Tôi không mơ về biển.

A simple yes/no question can be made by adding có ... không around the verb:

• Bạn có mơ về biển không?

For the original sentence with tôi, if you are asking for confirmation, you could say:

• Tôi có mơ về biển không?

But in real conversation, that sounds like you are asking Do I dream about the sea?, which is less common unless you are thinking out loud or asking rhetorically.

More naturally, you would ask another person:

• Bạn có mơ về biển không?

It is grammatical and natural, but it can sound a little poetic depending on context.

Why?

• mơ về... is normal
• biển is a vivid image
• the sentence is short and simple, which can make it feel literary or reflective

In everyday speech, people might also say longer versions like:

• Tôi nằm mơ về biển tối qua.
• Dạo này tôi hay mơ về biển.

So the sentence is correct, but its tone can feel calm, emotional, or poetic.