Завтра мы полетим к морю.

Полетим is the 1st person plural future form, meaning we will fly / we will set off flying.

It comes from the verb полететь, which is a perfective verb. In Russian, perfective verbs often describe a single complete action or the start of an action. So мы полетим suggests one specific trip in the future.

Russian has two common ways to talk about the future:

• Perfective future: one word
  
  • полетим = we will fly / we will set off
• Imperfective future: будем + infinitive
  
  • будем лететь = we will be flying

The sentence uses полетим because it presents the trip as a single future event. If you said Завтра мы будем лететь к морю, that would focus more on the process: Tomorrow we will be in the middle of flying toward the sea.

With verbs of motion, по- very often gives the idea of setting off, starting to go, or making a bounded single trip.

So:

• лететь = to be flying in one direction
• полететь = to set off flying / to fly off / to begin a flight

In this sentence, полетим sounds natural because it refers to beginning a specific journey tomorrow.

Because the preposition к requires the dative case.

The noun море means sea and is a neuter noun. Its dative singular form is:

• nominative: море
• dative: морю

So:

• к морю = to/toward the sea

This is a very common Russian pattern: after к, the following noun goes into the dative.

These prepositions give different meanings:

• к морю = toward the sea / to the seaside area
• в море = into the sea, literally into the water or out onto the open sea
• на море = often to the seaside / to the sea for vacation

So к морю suggests movement in the direction of the sea. It is not the same as into the sea.

In everyday Russian, на море is also very common when people mean going to the seaside for a holiday. But к морю is perfectly understandable and emphasizes direction toward the sea.

This is a very common question because Russian verbs of motion are tricky.

• лететь = to be flying in one direction, one trip
• летать = to fly in general, repeatedly, or in different directions
• полететь = to set off flying / to fly off; perfective, for a single completed future event

Examples:

• Я лечу в Москву. = I am flying to Moscow.
• Я часто летаю в Москву. = I often fly to Moscow.
• Завтра я полечу в Москву. = Tomorrow I will fly to Moscow.

So in your sentence, полетим fits because it refers to one specific future trip.

Yes. Russian often omits subject pronouns when the verb form already makes the subject clear.

So both of these are possible:

• Завтра мы полетим к морю.
• Завтра полетим к морю.

Because полетим already means we will fly, the pronoun is not strictly necessary.

Including мы can make the sentence a little clearer, more explicit, or slightly more contrastive, depending on context.

No, Russian word order is fairly flexible.

Завтра мы полетим к морю is a natural neutral order, with завтра placed first to set the time frame.

Other possible orders include:

• Мы завтра полетим к морю.
• К морю мы полетим завтра.
• Полетим к морю завтра.

These all mean roughly the same thing, but the emphasis changes:

• first position often gets more focus
• later position can sound less emphasized or more like added information

So the sentence order is natural, but not the only possible one.

Here завтра is an adverb meaning tomorrow.

It does not change form here, and it tells you when the action happens:

• Завтра = tomorrow
• мы полетим = we will fly
• к морю = toward/to the sea

So the whole sentence is structured very simply:

Tomorrow + we will fly + to the sea

A helpful stressed version is:

За́втра мы полети́м к мо́рю.

Main stresses:

• за́втра
• полети́м
• мо́рю

Very roughly in English-style transliteration:

ZAV-tra my pa-lee-TEEM k MO-ryu

A few pronunciation notes:

• мы sounds like my, but with a Russian ы sound, which has no exact English equivalent.
• In полетим, the stress is on the last syllable: -тим.
• In морю, the stress is on the first syllable: мо-.

Usually, yes, in normal modern context it strongly suggests travel by air.

The verb лететь / полететь literally means to fly. So if people are talking about a trip and use полетим, the natural interpretation is that they are going by plane or some other flying means.

If the trip were by car or train, Russian would normally use a different verb, such as:

• поедем = we will go by transport
• отправимся = we will set off
• поедем к морю = we will go to the sea (without saying exactly how, though often by vehicle)

So полетим is not just a general go; it really does convey fly.