abyssal

They are the summits of very lofty mountains which have their bases in an abyssal ocean.

Verily, wheresoever it is, it is in the Abyssal World, where there is neither end nor limit.

Oceanic islands are those, usually very small, found in the midst of the ocean, with abyssal depth all about.

The zonarial Radiolaria live floating at various depths between the pelagic and abyssal species ( 234).

It must be remembered that abyssal faunas are almost unknown among fossils.