"The Russian man hurries to the cold water and jumps into the water."
Translation:Az orosz férfi odasiet a hideg vízhez és beleugrik a vízbe.
Because it does not have the "completeness" sense that the man arrives at the water. "Odasiet" carries that meaning. The action ends at its intended destination/result.
siet a vízhez - he is hurrying to the water. He is on his way.
odasiet a vízhez - he hurries, and arrives at, the water
You could say "a vízhez siet", to have a similar meaning as "odasiet a vízhez".
There was some discussion on this topic here:
i and í are really difficult to describe in terms of vowel harmony, because they're really neutral (sometimes described as front vowels, sometimes as back vowels) and as we see here they're considered front vowels in this word. You mostly just have to memorize whether a word containing only i or í is front or back (fortunately there's not that many)
Ok, it's a bit more complicated than I thought while answering you (I ignored the fact I knew 'i' is something intermediate). Here you have a better explanation. http://www.hungarianreference.com/Vowel-Harmony.aspx
According to the article, i and í are front vowels but they behave as if they were back when there are no other vowels in a word.
So, basically in the case of víz you would be right. However, there's a bunch of short Hungarian stems that behave in a weird way, probably because they used to contain different sounds in the past. Those you have to remember and I think in this case víz is one of them (compare with Finnish "vesi").
But Hungarian, like Finnish, is a Finno-Ugric language, as opposed to those Indo-European like Russian or English. Therefore, it's the first one to be compared if we want to try guessing the way the words evolved. Other Finno-Ugric languages include:
Khanty (close kinship) - йӛӈк/йиӈк (the dictionary gives both forms; ӛ is a central vowel - neither front nor back one); source: glosbe.com
Mansi (close kinship) - vit; source: Wikipedia
Estonian (some kinship) - vesi; source: Google Translate
Veps (some kinship) - vezi; source: glosbe.com
There are some other Uralic languages, with various words for water, but I think Khanty and Mansi are enough. Some guy from Hungary I met told me that the "í" in some words may originate from other sounds and that's why they behave like front vowels there. Again, Finnish gives us examples that give us a hint that some short stems may have just dropped some vowels over time hence the way harmony works for them:
kirjoittaa - ír
silta - híd
OK, there is little similarity if there’s any, but still. If it is fine as an explanation for you, then OK, if not, that’s also alright.
Then, what the article about vowel harmony on Wikipedia says, is:
'Some 1-syllable Hungarian words with i, í or é are strictly using front suffixes (gép|re, mély|ről, víz viz|et, hír|ek), while some others can take back suffixes only (héj|ak, szíj|ról, nyíl nyil|at, zsír|ban, ír|ás)'
So to sum it up it’s just something we have to learn each time we learn a word. TBH even native Hungarians don’t know why it is like that xD