Cumujemy przy brzegu rzeki, tym bardziej że nurt jest szybki.

Cumujemy is the 1st person plural present-tense form of cumować.

So it means we are mooring / we moor / we dock.

A few useful points:

• cumować = to moor, to berth, to dock
• cumujemy = we do that
• Polish often omits the subject pronoun, so there is no need to say my cumujemy unless you want emphasis.

Because Polish present tense can cover both a general present and an action happening now, cumujemy could mean either:

• we are mooring
• we moor
• depending on context, even we’re going to moor here in a practical, immediate sense

In Polish, the verb ending usually shows who the subject is, so the subject pronoun is often left out.

Here, -my in cumujemy already tells you the subject is we.

Compare:

• cumuję = I moor
• cumujesz = you moor
• cumujemy = we moor

So adding my would usually only be for contrast or emphasis:

• My cumujemy przy brzegu, a oni płyną dalej.
  We are mooring by the bank, and they are sailing on.

Because przy takes the locative case.

The base noun is:

• brzeg = bank, shore, edge

After przy, it changes to the locative singular:

• przy brzegu = by / near the bank

This is a very common pattern:

• przy stole = at the table
• przy oknie = by the window
• przy drodze = by the road
• przy brzegu = by the bank

So the important rule is:

• przy + locative

Because rzeki is in the genitive case after another noun.

The phrase brzeg rzeki literally means the bank of the river.

So:

• brzeg = bank
• rzeka = river
• rzeki = of the river

Then, because przy forces brzeg into the locative, you get:

• przy brzegu rzeki = by the bank of the river

So two things happen at once:

1. przy changes brzeg to brzegu
2. rzeka becomes rzeki because it depends on brzeg as of the river

Tym bardziej że is a fixed expression meaning something like:

• all the more so because
• especially since
• particularly because
• all the more because

It introduces a reason that strengthens what was just said.

In this sentence:

• Cumujemy przy brzegu rzeki, tym bardziej że nurt jest szybki.

the second clause explains why mooring by the bank makes even more sense: the current is fast.

So the idea is not just simple cause, but an added reason that makes the decision even more justified.

Good question. They all can introduce a reason, but the nuance is different.

• bo = because
• ponieważ = because / since, a bit more formal
• tym bardziej że = all the more because / especially since

Compare:

• Cumujemy przy brzegu, bo nurt jest szybki.
  We’re mooring by the bank because the current is fast.

• Cumujemy przy brzegu, tym bardziej że nurt jest szybki.
  We’re mooring by the bank, especially since the current is fast.

The second version suggests:

• there may already be a reason to moor there,
• and the fast current is an extra strong argument.

So tym bardziej że is not just neutral cause; it adds emphasis.

Nurt means the current of a river or stream, especially the moving flow of water.

It is related to prąd, but they are not always interchangeable.

• nurt = current, flow, stream current, often specifically in a river context
• prąd = current too, but can also mean electric current

In river language:

• nurt rzeki = the current of the river

So nurt is a very natural choice here because the sentence is about mooring by a riverbank.

Because szybki is an adjective, and here it describes the noun nurt.

• nurt = a noun
• szybki = an adjective meaning fast

So:

• nurt jest szybki = the current is fast

If you used szybko, that would be an adverb, meaning quickly / fast in the sense of how something happens.

Compare:

• Nurt jest szybki. = The current is fast.
• Łódź płynie szybko. = The boat is moving fast.

Also, nurt is masculine singular, so the adjective must match:

• szybki = masculine singular nominative

It is a normal and correct verb, but it is specialized vocabulary connected with boats, ships, harbors, and waterways.

So a native speaker will understand it, but it is not an everyday verb for all situations. It belongs to a nautical context.

Related words:

• zacumować = to moor / tie up successfully, often perfective
• cumowanie = mooring
• cumy = mooring lines

If you are talking about boats, cumować is exactly the right kind of word.

Because że introduces a subordinate clause, and in Polish that is normally separated by a comma.

Here the structure is:

• main clause: Cumujemy przy brzegu rzeki
• subordinate clause: tym bardziej że nurt jest szybki

So the comma is standard and expected.

This is very similar to other Polish patterns such as:

• Wiem, że ma rację. = I know that he is right.
• Zostajemy, ponieważ pada. = We are staying because it is raining.

Yes, Polish word order is flexible, though some versions sound more natural than others.

The original:

• Cumujemy przy brzegu rzeki, tym bardziej że nurt jest szybki.

is natural and clear.

You could also say:

• Tym bardziej cumujemy przy brzegu rzeki, że nurt jest szybki.

but that sounds less neutral and more marked stylistically.

Or:

• Cumujemy przy brzegu, bo nurt rzeki jest szybki.

This changes both wording and nuance.

So yes, word order can change, but the original sentence has a very natural informational flow:

1. what we are doing
2. extra reason for doing it

Formally, cumujemy is present tense, but in context it can sometimes refer to an immediate planned action, especially in practical speech.

For example, if people are on a boat deciding what to do right now, Cumujemy przy brzegu can mean something like:

• We’re mooring by the bank
• Let’s moor by the bank
• We’ll moor by the bank now

Polish often uses present forms in this kind of immediate, action-oriented context.

So grammatically it is present, but context may give it a near-future or decision-making flavor.

Here are the main forms:

• cumujemy → cumować
• przy → preposition przy
• brzegu → brzeg
• rzeki → rzeka
• tym bardziej że → fixed expression
• nurt → nurt
• jest → być
• szybki → szybki

This is a useful habit in Polish: when you meet a sentence, try to identify both:

1. the dictionary form
2. the case or conjugated form actually used in the sentence

That helps a lot with reading and building your own sentences.