I keep my coins in a sinkhole on Oak Island.
I
had to
Google that:
"Oak Island is a 140-acre (57 ha) island in Lunenberg County on the south
shore of Nova Scotia,
Canada. Oak Island is noted as the location of the so-called
Money Pit, a site of numerous excavations to recover treasure believed by many to be buried there. The island is privately owned, and advance permission is required for any visitation. Several documented treasure recovery attempts have found layers of apparently man-made artifacts as deep as 31 meters, but ended in collapsed excavations and flooding. Critics argue that there is no treasure and that the pit is a natural phenomenon, likely a sinkhole".