It looks as if there were unsoundable depths in some places and shoals in others.    From Wordnik.com.  [Among the Forces] Reference

If we cannot solve the problems of the present existence of worlds, how little can we expect to fathom the unsoundable depths of their creation and development through ages measureless to man!.    From Wordnik.com.  [Recreations in Astronomy With Directions for Practical Experiments and Telescopic Work] Reference

After a fearful progress across cracked rocks and bogs, past abysses of unsoundable depths -- on the very edges of which my mule maliciously walked as though to mark them out with her shoes -- we arrived, by an almost perpendicular descent, at the end of our journey.    From Wordnik.com.  [The Nabob] Reference

During the days that followed his arrival at Ronda and release from the prison there, Frederick Conyngham learnt much from his host and little of the man himself, for General Vincente had that in him with which no great leader in any walk of life can well dispense -- an unsoundable depth.    From Wordnik.com.  [In Kedar's Tents] Reference

And again he exclaims – Mexicans! my heart feels itself wounded by the deepest grief, and all humanity shudders in contemplating the unsoundable chaos of evils in which the authors of this rebellion have sunk the incautious men whom they have seduced, in order to form with their dead bodies the bloody ladder which was to raise them to their aggrandizement!.    From Wordnik.com.  [Life in Mexico, During a Residence of Two Years in That Country] Reference

And again he exclaims -- "Mexicans! my heart feels itself wounded by the deepest grief, and all humanity shudders in contemplating the unsoundable chaos of evils in which the authors of this rebellion have sunk the incautious men whom they have seduced, in order to form with their dead bodies the bloody ladder which was to raise them to their aggrandizement!.    From Wordnik.com.  [Life in Mexico] Reference

Can sound the seas unsoundable, the skies.    From Wordnik.com.  [Songs of the Springtides and Birthday Ode Taken from The Collected Poetical Works of Algernon Charles Swinburne—Vol. III] Reference