Claustrophobia: De Profundis is an expansion for Croc's Claustrophobia that adds more components and more choices to the game without adding many new rules.

New components include a 55-card deck with new talents for the Brother Redeemer, new demons, new events, new objects; ten new room tiles, with six new types of rooms (sanctified zone, demon pit, tomb of the ancient warrior); four painted figures and additional markers; and twelve new scenarios with playtimes ranging from 30 to 90 minutes.

As for new rules, the demon player's hand size is reduced to three (due to powerful new event cards), Siccaria skills are now permanent, and a new beast is introduced.