  We present exact Coleman-de Luccia (CdL) instantons, which describe vacuum
decay from Anti de Sitter (AdS) space, de Sitter (dS) space and Minkowski space
to AdS space. We systematically obtain these exact solutions by considering
deformation of Hawking-Moss (HM) instantons. We analytically calculate decay
rates and discuss a subtlety in the interpretation.
