How many letters does the top answer for “of or relating to or happening on the bottom under a body of water” have?

The most common answer is benthal (7 letters).

Crossword clue: of or relating to or happening on the bottom under a body of water

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

benthal 7 letters wn-def

of or relating to or happening on the bottom under a body of water

benthic 7 letters wn-def

of or relating to or happening on the bottom under a body of water

benthonic 9 letters wn-def

of or relating to or happening on the bottom under a body of water