Μετά τη θάλασσα κάνω ντους με κρύο νερό, γιατί οι ώμοι μου και το δέρμα μου νιώθουν καλύτερα έτσι.

Literally, yes: after the sea. But in natural English, it usually means something like after being in the sea, after swimming in the sea, or sometimes after the beach/seaside.

Greek often uses θάλασσα in places where English might choose the sea, the beach, or going swimming, depending on context.

Because η θάλασσα is the dictionary form of the noun, called the nominative.

After μετά meaning after, Greek uses the accusative form. So:

• η θάλασσα = the sea as a subject
• τη(ν) θάλασσα = the sea after a preposition like μετά

So μετά τη θάλασσα is grammatically correct.

Not here.

In everyday Greek, μετά can be followed directly by the accusative:

• μετά το φαγητό = after the meal
• μετά τη δουλειά = after work
• μετά τη θάλασσα = after the sea / after swimming

You may also hear μετά από in other contexts, but μετά τη θάλασσα is perfectly natural.

Because the final -ν of την is often dropped before certain consonants, including θ.

So:

• τη θάλασσα is the normal form here
• την is kept more often before vowels and some other consonants

This is a very common feature of modern Greek spelling and pronunciation.

This is just the standard Greek expression for take a shower.

Greek often uses κάνω + noun where English uses take or have:

• κάνω ντους = take a shower
• κάνω μπάνιο = bathe / have a bath / go for a swim, depending on context

You can also say κάνω ένα ντους, which is similar to have a shower.

It means with cold water or using cold water.

Here, με means with, and it shows the means or material used.

Also, κρύο is neuter singular because it describes νερό, which is a neuter noun:

• το νερό = the water
• κρύο νερό = cold water

Because Greek normally uses the definite article with possessed nouns.

So:

• οι ώμοι μου = my shoulders
• το δέρμα μου = my skin

This is the normal Greek pattern. In English, we usually just say my shoulders, but Greek usually keeps the article too.

Because each noun normally takes its own possessive.

So Greek naturally says:

• οι ώμοι μου και το δέρμα μου

rather than leaving the second μου out.

Repeating it makes the sentence clearer and more natural.

Because it introduces the reason for the action:

• κάνω ντους... γιατί... = I take a shower... because...

In Greek, γιατί can mean both:

• because
• why

The structure of the sentence tells you which meaning is intended.

Because the subject is made of two things joined by και:

• οι ώμοι μου
• το δέρμα μου

Together, they form a compound subject, so Greek uses a plural verb:

• οι ώμοι μου και το δέρμα μου νιώθουν...

Even though το δέρμα μου is singular, the whole subject is plural because it includes two items.

Because after verbs like νιώθω and αισθάνομαι, Greek very often uses καλύτερα, the adverb meaning better.

So:

• νιώθω καλύτερα = I feel better
• οι ώμοι μου νιώθουν καλύτερα = my shoulders feel better

This is very natural Greek, just like English says feel better, not feel more good.

It means like this, this way, or that way.

In this sentence, it refers to the whole idea of taking a shower with cold water after the sea. So the sense is:

my shoulders and skin feel better that way

Yes. Greek word order is more flexible than English word order.

This sentence begins with Μετά τη θάλασσα to set the scene first: after the sea.

That sounds very natural, but Greek could rearrange parts of the sentence for emphasis or style. The version you have is clear and idiomatic.

Yes, you probably could.

Both νιώθω and αισθάνομαι can mean feel. In everyday speech, νιώθω is very common and natural.

So νιώθουν καλύτερα sounds completely normal here.