slough of despond

noun2

1. •
   A dreary bog or marsh.
2. •
   (figurative) A state of disheartening hopelessness; pit of despair.

   • Only after he had ceased dreaming of them and thrown off his crushing burden of transcendental morality – only thus and then could he hope to rise out of the slough of despond in which he wallowed. — 1908