rough sea; stormy sea
Describes a sea with high waves and strong winds, often in literary or news contexts.
荒海を航海するのは危険だ。
Sailing on rough seas is dangerous.
台風で
The typhoon turned the sea rough.
荒海 refers to the rough sea itself as a place, while 荒波 refers to the violent waves (literal or figurative) rather than the sea.
Compound of 荒 (rough, wild) and 海 (sea).