polynya
A naturally formed transient area of open water surrounded by sea ice, especially in polar or subpolar seas.
We immediately ascended a hill, and saw that the supposed land was nothing but hummocks of ice, piled up beyond a large Polynia, or space of open water, which extended from east to west, as far as the eye could reach.
Where it comes from
Borrowed from Russian полынья́ (polynʹjá, “polynya”) in the 1850s, from Middle Russian полыньѧ (polynʹja) (att. in 1639), from полыи (polyi, “open from above, uncovered; hollow”), whence also Russian полый (polyj, “hollow”), from Old East Slavic полъ (polŭ, “uncovered”), ultimately from Proto-Indo-European *pleh₂- (“flat”). The rare plural form polynyi is borrowed from Russian полыньи́ (polynʹí).
Adapted from the Wiktionary entry polynya (CC BY-SA 4.0).