underseas

[ uhn-der-seez ]

/ ˌʌn dərˈsiz /

beneath the surface of the sea.

Origin of underseas

First recorded in 1675–85; undersea + -s¹

You can look through the underseas ports and watch me, Rawlins reminded them.

The Radio Detectives Under the Sea |A. Hyatt Verrill
The first underseas cable was laid in 1851 between France and England.

The Outline of History: Being a Plain History of Life and Mankind |Herbert George Wells
But there was little time for such thoughts, as this underseas mission concerned the lives of nine young people.

Sign of the Green Arrow |Roy J. (Roy Judson) Snell
That the underseas craft had been struck was indicated clearly enough by the patches of oil on the water.

Dave Darrin After The Mine Layers |H. Irving Hancock

A collision while underseas in a submarine is a serious matter.

The Heads of Apex |Francis Flagg