also: うなはら
noun
A somewhat literary or poetic word for the vast open sea, often evoking a sense of boundlessness. In modern usage it appears in elevated descriptions, literature, and set phrases.
船は広い海原を進んでいった。
The ship sailed across the vast ocean.
水平線まで続く海原を見つめた。
I gazed at the sea stretching to the horizon.
Obsolete kana usage; the same kanji form was historically read うなはら.
Compound of 海 (う, 'sea') + 原 (はら, 'plain, field'), with the reading うなばら arising from rendaku voicing of はら to ばら. The older reading うなはら preserves the unvoiced form.