The phrase "bottomless depth" is correct and usable in written English.
It can be used to describe an immeasurable or infinite extent, often in a metaphorical sense, such as in literature or poetry.
Example: "The ocean's bottomless depth seemed to hold secrets that no human could ever uncover."
Alternatives: "endless abyss" or "infinite depth."
Picture walking about in freezing, absolute darkness in a place that shrinks and expands, a place where staircases suddenly sink away to bottomless depths or compress to flatness.
Tracked pontoons, driven through and over the ice-features called sastrugi – described as like crossing a corrugated roof – would start to disintegrate; stuck in a crevasse, they risked vanishing into bottomless depths.
The classic romantic triangle may never have been so ethereal; Malick's balletic camera conjures love's rhapsodic heights and bottomless depths and turns the glowing light of the American landscape into a spiritual bounty.
Jellyfish have adapted to all types of waters from warm shallow waters, all the way to the bottomless depths of the sea.
It's only after I wash my hands and my glasses and search around the bottomless depths of my purse, the size of which could match Hermione Granger's, that I realize something is missing.
A similar set of terms are reeled out with a lulling repetition; the athlete's 'deepest sympathy' is extended to the family of Reeva Steenkamp over and over in a series of sensitive and thoughtful missives which not only reassure the victim's bereft loved ones, but also the world's media as to the bottomless depths of Pistorius' well of tears.
Underground lakes reflected ceiling formations with crystal clarity, making the water seem bottomless instead of its actual depth of 2 to 10 inches.
Thoreau noted that his fellow Concordians once thought the pond bottomless, and staring into the milky-green depths I can understand why.
They plunge to depths of 198 feet — early settlers thought them bottomless.
Thoreau sounded the pond, which was thought to be bottomless, and produced a detailed and accurate chart showing the depths and shape of the lake bed.
