expression
bottomless; unfathomable; immeasurable
Describes something so deep or vast that its limits cannot be perceived, often used figuratively for potential, power, or depth of feeling. Related to the literary form 底知れぬ.
See also: 底知れぬ
彼の才能は底知れず、どこまで伸びるかわからない。
His talent is bottomless; there's no telling how far he'll go.
The lake is said to be of unfathomable depth.