Undine is a physicist, sex worker, activist – and one of the defining voices of the German sex work scene. She started out as a striptease dancer, later ran one of Hamburg’s best-known BDSM studios, and is a founding member of the Professional Association for Erotic and Sexual Services – Europe’s largest sex worker advocacy group. Today, she looks back on almost three decades of experience in sex work – in SM studios, strip clubs, brothels, at sex parties, as an escort, online and in private rooms.