How many letters does the top answer for “situated at or extending to great depth; too deep to have been sounded or plumbed” have?

The most common answer is unfathomed (10 letters).

Crossword clue: situated at or extending to great depth; too deep to have been sounded or plumbed

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

unfathomed 10 letters wn-def

situated at or extending to great depth; too deep to have been sounded or plumbed

unplumbed 9 letters wn-def

situated at or extending to great depth; too deep to have been sounded or plumbed