Deciding to try cliff diving with no safety procedures in place and no experience is an example of something that would be described as a foolhardy activity.
Origin of foolhardyMiddle English folhardi from Old French fol hardi from fol, fool + hardi: see hardy
Origin of foolhardyMiddle English folhardi from Old French fol hardi fol fool ; see fool . hardi bold ; see hardy 1.
(comparative foolhardier or more foolhardy, superlative foolhardiest or most foolhardy)