(plural) the deepest and most remote part
"from the depths of darkest Africa"
"signals received from the depths of space"
plural of depth
"The submarine descended into the dark depths of the ocean trench."
The deepest part. (Usually of a body of water.)
In plain English: The depths are the deepest part of something, usually referring to how far down you can go into water or how intense an emotion feels.
"The depths of the ocean were dark and mysterious to anyone who had never seen them before."
Usage: Use depths to refer specifically to the lowest or most remote parts, such as the deep end of an ocean or the furthest reaches of a forest. Avoid using it for general distance unless emphasizing extreme remoteness rather than simple length.