noun
depths of the earth; underground depths
Refers to the deep interior of the earth, often with a sense of vastness or mystery. Used in both literal and figurative contexts.
地底にはまだ多くの未知の世界が広がっている。
Many unknown worlds still lie in the depths of the earth.
その小説は地底探検をテーマにしている。
The novel is about an expedition into the depths of the earth.