Yes, we walked on the ocean floor! From Saint John, New Brunswick, Canada, 18 August 2014:

The tides in the Bay of Fundy are extreme—the highest differential in the world, I believe. High tide today is nearly 9 meters at 6:56 am. Low tide, at 1:05 pm, is less than 2 meters. Our tour, St. Martins and the Bay of Fundy, will span both.

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At low tide we went to the beach, where we had a wonderful lunch at Caves Restaurant. We then walked down the vast rocky shore to the sea caves, which were carved out from many years worth of tidal action.