Learn Hardcore Turkish: Jeotermal kaynak suyuyla dolu havuzda yüzmek bütünsel bir rahatlama sunuyor. - Swimming in the pool filled with geothermal spring water offers holistic relaxation.

jeotermal means “geothermal”
kaynak means “spring,” and suyu is “water” with the third-person possessive suffix (so “spring water”)
-yla is the instrumental suffix (short form of -ile), meaning “with”
dolu is an adjective meaning “filled” or “full”
Put together, jeotermal kaynak suyuyla dolu = “filled with geothermal spring water.”

What case is expressed by the suffix -yla on suyu, and why is it used here?

The suffix -yla is the instrumental case, indicating “with.” It shows the means or material: “with geothermal spring water.” You attach -yla (or -yle, -la, -le depending on vowel/consonant harmony) directly to the noun.

Why is dolu placed after suyla, and what role does it play?

dolu is an adjective meaning “full” or “filled with.” In Turkish, participle-like adjectives formed with dolu typically come after the noun phrase they describe. Here suyla dolu forms a compound adjective (“filled with water”), and it precedes havuz (“pool”) to modify it: suyla dolu havuz = “pool filled with …”

What is the function of havuzda in this sentence?

-da is the locative case suffix meaning “in.” So havuzda means “in the pool.” It tells us where the action (yüzmek, “to swim”) takes place.

Why is yüzmek in the infinitive form rather than a conjugated form?

In Turkish, the infinitive (dictionary) form with -mek/-mak can act as the subject of a sentence when followed by a conjugated main verb. Here Havuzda yüzmek (“swimming in the pool”) is the subject, and the main verb sunuyor agrees with it.

How is bütünsel formed, and what does it mean?

bütün means “whole.”
Adding the adjective-forming suffix -sel yields bütünsel, meaning “holistic” or “integral.”
So bütünsel = “holistic.”

What is the tense and person of sunuyor, and which verb is it from?

Sunuyor is the present continuous tense of the verb sunmak (“to offer, to present”). It breaks down as:

sun- (root)
-uyor (present continuous suffix, harmonized from -iyor)
No additional ending is needed for third-person singular, so sunuyor = “he/she/it offers.”

Could you replace sunuyor with another verb like sağlıyor, and would the nuance change?

Yes. Sağlamak means “to provide” or “to supply.”

bütünsel bir rahatlama sunuyor = “offers a holistic relaxation” (a bit more formal, “presents”)
bütünsel bir rahatlama sağlıyor = “provides a holistic relaxation” (emphasizes the act of providing)
Both are correct; the nuance is subtle.

Why is the adjective bütünsel placed before rahatlama, and is that standard?

In Turkish, adjectives normally precede the nouns they modify. Bütünsel (“holistic”) modifies rahatlama (“relaxation”), so the order bütünsel bir rahatlama is standard: “a holistic relaxation.”

Can we simplify jeotermal kaynak suyuyla dolu havuz to jeotermal havuz, and what is lost?

You could say jeotermal havuz (“geothermal pool”), but that phrase omits that the pool is specifically filled with spring water. The original emphasizes the material of the pool (spring water), which might be important if you want to highlight the therapeutic quality of kaynak suyu.