The Cocoon Nebula, Sh2-125, is involved with open star cluster IC 5146, and lies at the end of an interesting dark nebulae, B 168 in Cygnus.The nebula, which includes reflection and emission nebulosity and is bisected by a dark lane, is faint and only visible in telescopes. The cluster is not very rich, containing only about 20 stars, the brightest of which is about magnitude 9.6. The dark nebula B 168, however, is easily visible in binoculars and is a fascinating object amidst the rich Cygnus star fields, about 3 degrees east-southeast of open cluster M39.