A US Navy eBook reading device, NeRD, offers eBook reading for Navy Submarines.
For security reasons the Navy offers this E Ink device with 300 preloaded eBooks. Nothing fancy but basic recreation reading when library space is at a premium. The is a completely closed product with no memory slots or other communication capabilities.
NeRD was developed by the Navy General Library Program (NGLP) in partnership with Findaway World, a Solon, Ohio-based firm that built a platform for preloaded content on secured devices. They are also in partnership with book publishers to provide the content. While the NGLP is providing the NeRD and other library services free of charge to officers, sailors and their families, it will not be available for civilians.
Update: They have now moved to the Playaway#Lock reader.