Learn Hardcore Turkish: Yüzme havuzu jeotermal kaynak suyuyla besleniyor. - The swimming pool is supplied with geothermal spring water.

Yüzme is the noun (gerund) form of yüzmek (“to swim”), created with the noun-forming suffix -me, so it means “swimming.” Placed before havuz (“pool”), it makes the compound yüzme havuzu = “swimming pool.”

What is jeotermal kaynak suyu, and how do its parts break down?

Jeotermal = “geothermal” (from geo– + thermal).
Kaynak = “spring” (a natural water source).
Jeotermal kaynak = “geothermal spring.”
Su = “water.” Adding the 3rd person-sg possessive -u gives suyu = “its water” or “the water of (the) spring.”
Altogether, jeotermal kaynak suyu = “geothermal spring water.”

How is suyuyla formed, and why is there a buffer y?

Start with su (“water”).
Add the 3rd person-sg possessive -u → suyu (“its water” or “the spring’s water”).
Attach the instrumental suffix -la (“with/by”).
Because suyu ends in a vowel, Turkish inserts a buffer consonant y before -la.
Result: su + -yu + y + -la = suyuyla = “with (its) water.”

What does besleniyor mean, and how is it constructed?

The base verb is beslemek = “to feed.”
Adding the suffix -n turns it into beslenmek, a middle/passive form meaning “to be fed” or “to feed oneself.”
Then add the present-continuous marker -iyor (with the vowel harmonized as -en + iyor).
Finally, 3rd person-sg has a zero ending after -iyor.
So besleniyor = “is being fed” or more naturally “is being supplied.”

Is beslenmek passive? Who or what is doing the feeding?

Yes. Beslenmek is the passive/middle derivation of beslemek. There is no explicit agent here; the sentence simply states that the pool receives its supply. The phrase jeotermal kaynak suyuyla tells us by what means (with spring water) the pool is fed.

Why is there no pronoun, and how do we identify the subject?

Turkish often drops subject pronouns when the verb ending makes the person clear. In the present continuous, 3rd person-sg uses a zero ending after -iyor, so besleniyor already implies “it is being fed.” The noun Yüzme havuzu has no case suffix (nominative), so it’s the subject.

Why use the instrumental -la here? Could we use the ablative -dan instead (suyundan)?

The instrumental -la expresses means: “with/by spring water” → suyuyla.
The ablative -dan marks origin/separation: “from the water,” which would wrongly suggest the pool is emptied from the water.
Hence suyuyla is correct for “fed with water.”

Is the word order fixed? Could I say Jeotermal kaynak suyuyla yüzme havuzu besleniyor?

Turkish generally uses Subject–Adjunct–Verb, so Yüzme havuzu jeotermal kaynak suyuyla besleniyor is the neutral order. You can front jeotermal kaynak suyuyla for emphasis (Jeotermal kaynak suyuyla yüzme havuzu besleniyor), but it shifts the focus onto the water source and sounds more marked.