In 1981, TSR published the module named “The Sinister Secret of Saltmarsh” with the module code “U1”. It was written by Dave J. Browne and Don Turnbull, and illustrated by Dave De Leuw, Harry Quinn, and Stephen D. Sullivan. It consisted of a 32 page booklet and tri-fold cover with maps.
This conversion guide allows DMs to run the original module with 5th Edition rules and provides a reference sheet for encounters.
To use this conversion guide you will need a copy of U1: The Sinister Secret of Saltmarsh.