not just a place in "The Phantom Tollbooth"

Doldrums - an area of the Atlantic Ocean and the Pacific Ocean affected by the Intertropical Convergence Zone, a low-pressure area around the equator where the prevailing winds are calm. In colloquial usage, "being in the doldrums" refers to being in a state of listlessness, despondency, inactivity, stagnation, or a slump. (from wikipedia.org)