Translation:Where does the sea end and the sky begin?
Dobrý den ! Místo "begin" jsem použil "start" v angličtině. Možná bylo to nepřesné ale kdybyste to mohli přípustit jako synonym, aspoň se to už ostatním za chybu počitat nebude. Předem děkuji ;)
This translation uses "does" to emphasize the intention of the question. I wrote it without "does" and with "start" instead of "begin". (reported)
I am using "begin" only in temporal context in English, while I use "start" in spatial contexts, too.
There is a report from yesterday for "where ends the sea and starts the sky," which perhaps is yours. I (native AmE) would say it's quite poetic and not very likely to be used in "everyday" speech or writing. It is, however, a lovely translation, and I would not oppose adding it if the CZ natives feel it accurately reflects the meaning of the original sentence.