A subsea wellhead structure including a casing hanger having an exterior downwardly facing shoulder for landing within a well bore, a central bore, means for connecting a casing thereto, an upper exterior surface tapering downwardly and outwardly, and an external surface below said shoulder tapering downwardly and inwardly for centering said hanger on landing, a seal assembly with a metal seal sleeve having downwardly extending fingers, an internal metal annular bulbous sealing surface and an external metal cylindrical sealing surface, means for latching said seal sleeve in sealing position, a protector sleeve and means for releasably securing said protector sleeve to said seal assembly and said latching means, the latching means including retaining means preventing premature setting or movement of the latching means prior to the setting of said sealing means.