superdeep
Adjective
Meaning
English Wikipedia has an article on:Kola Superdeep BoreholeWikipedia
superdeep (not comparable)
Extremely deep
Examples
The deepest borehole in the world is Kola Superdeep Borehole at convert.
The deepest hole drilled to date is the Kola Superdeep Borehole citation with a drill-depth of more than 7.5 miles (12 kilometers).