of the mariana trench's oceanic depths

abyss deep sea mariana trench ocean depths underwater exploration darkness marine life pressure mysterious ecosystem bioluminescence creatures aquatic geology chasm discovery research expedition extreme abyssal plain submersible deepsea fauna flora unique habitats study currents marinebiology unknown trenchwall abyssopelagic abyssalmountains watercolumn deepdiving biodiversity oceanfloor sediment isolation vastness illustration trench's oceanic depiction