Here's an adventure lesson for all of you who have yet to learn it: The most dangerous moments often arise out of the most unassuming circumstances. Just ask these hikers, who took to the hills above Maui for a quick dip in Commando waterfall only to be greeted by an entirely unexpected flash flood that blocked their path back down the mountain and required rescue by helicopter. Needless to say, the footage captured on their drone is pretty terrifying but well worth a watch for anyone lacking a healthy respect for the raw power of nature.