I think that would have to be when we were visiting some of the Hawaiian islands in 1985, Hawaii, Kauai and Oahu. We were on Kauai, and visiting Barking Sands beach on the far side of the island, near the NaPali coast. I was out in the surf bodysurfing, with my wife, so I needed to take the key to the rental car with me, and had it in a velcro closed pocket. Got out of the water, and it was lost in the surf. Had to hitchhike back to the airport, rent another car, pick up my wife, drop off the extra rented car, and return. Made a 3 hr. trip to the beach into a 10 hr. adventure.