(idiomatic) Ocean conditions that are very windblown and messy, possibly to the point of being inimical to surfing and other watersports.

Any unidentified sea monster, especially one resembling a snake or dragon.

An inland sea in Indonesia that is part of the Pacific Ocean and is between the islands of Buru and Ceram.

A sea north of the island of Java in Indonesia and south of Borneo.

The Arctic Ocean.

The nominal height of the surface of the oceans above which heights of geographical features and aircraft flight levels are measured.

A sea in British Isles, Europe, in the Atlantic. A sea between the islands of Great Britain and Ireland; bordered to the north by the North Channel and to the south by St George's Channel and the Celtic Sea.

Marine blue-green algae (cyanobacteria, actually brown coloured) of the genus Trichodesmium.

Any sessile tunicate, of the class Ascidiacea, which squirts water from two openings when touched; they are filter feeders

Frozen seawater.