From the publisher's website.
For centuries, Nimmerland (and its surrounding minor islands) lay in relative obscurity. Though spitting distance from several waterborne trade routes, its location (even its existence) was a secret kept by the derelicts, deserters, smugglers, pirates, and recluses that called it home. However, it has recently been “discovered” by the outside world and dubbed “Nimmerland,” the land that was “never” there.
Included are background information, adventure seeds, and wandering monster charts for the various areas of Nimmerland (Nimmer Isle, the Lower Jungles, the Upper Plains, Pirates Cove, Vamwalye Forest, Bear Canyon, Mermaid Lagoon, Aglar Bog and the smaller surrounding islands).