A giant swamp-land on Wunderland populated by crocodilians and an assortment of other dangerous predators. The swamp's center is actually a series of ancient meteor craters. The swamp is filled with islands of differing heights as well as water of varying depths making an accurate survey, even from space, very difficult. Underground springs, rivers, and even the sea feed into Grossgeister swamp, and there are wide stretches of open water, although in other areas there are miles wide stretches of vegetation.
More rural-minded humans lived around the edge of the swamp even before the Kzin invasion. After the fall of Wunderland feral humans were known to make parts of the swamp their home, though no part of the swamp has ever really been tamed. After the liberation of Wunderland in 2420 CE many Kzin who wished to avoid human contact moved into the swamp, subsisting mostly from fishing. 
In 2430 CE a renegade group of Jotoki from a crashed Kzin ship began to prey on humans and Kzin living in and around the swamp. Vaemar Riit, accompanied by a group of students from Munchen University and a Kzintosh called Swirl-Stripes went to investigate the disappearances. They were able to reveal the hidden Jotoki colony that had now grown to dozens of individuals. A battle ensued during which much of their equipment was destroyed and Swirl Stripes was killed, along with a student calling herself Rosalind who may or may not have been a rebuilt version of the fugitive human Henrietta. The Vaemar and the rest of the group were able to escape, destroying the ship and the Jotoki colony in the process, although they were able to retrieve a few Jotok tadpoles before the destruction of the ship.