From the publisher:
The mysteries of the Spelljammer campaign are revealed! The greatest ship in the galaxy flies as a legend through the dark reaches of space, and now players can learn everything there is to know about it.
This boxed set contains complete deck plans of the most famous ship in space, and descriptions of the creatures that live within it. Over 200 pages of information and adventures to challenge the best spelljammers.
The "Legend of Spelljammer" contains:
a 32-page book of legends and statistics about the Great Ship;
a 64-page guided tour of the citadels, towers, and communities that crowd the back of the Spelljammer
a 96-page book of new ships and nonplayer characters, plus adventures aboard the Spelljammer
two maps revealing the ship's citadels
10 full-Color cards showing new ships and their deck plans
a 2-page card "DM's Summary of NPSs Onboard the Spelljammer"