Not to be confused with The Neverlands. This is an area on the Circle Sea coast of Quirm which appears to be contiguous with the maquis country described in the text. A substantial loop of the railway runs through here. Interestingly, we are informed that one other local peculiarity that absolutely meant the railway had to be re-routed in Quirm was a whole area completely inhabited by Zombies. No other information is given by Mrs Bradshaw. It is described in The Compleat Discworld Atlas as a place with little dry land, none of it permanent, where the indigenous people live and work on rafts, even mooring rafts to act as cultivatable gardens. The Society of Apothecaries is really excited by the Netherglades and describes it as "the natural pharmacopoeia of the world".
On Roundworld, Zombies are strongly associated with tropical or sub-tropical areas once colonised by the French: Haiti and Louisiana in the Caribbean. This appears to be another of those places analogous to parts of the Americas which Sir Terry once decreed that the Discworld should not have.