Of the real caches I've found so far (discounting virtual/locationless ones) the best one I've been to is GC5D5F - "Geocache" by Andy & Curtis.
OK, the name could use some improvement , but it's location is beautiful - on the side of a steep hill on the shoreline overlooking the Bay of Fundy, near St John, NB. The cache is about 10 metres up from the water pounding on the rocks & shoreline. Can be done when tide is up, but I approached it from below, during low tide.
GPComd.
Contents under pressure, do not puncture.