Heading to Wakayama any time soon? If so, dont forget to send me a
squid flavoured postcard from the
deepest underwater mailbox on record... pfft, as if you'd forget!
The mailbox is located 10m beneath Susami Bay with mail being sent by means of special waterproof plastic postcards. The mailbox is officially part of the Susami post office, taking 200 peices of mail a day in busy times, and it even has a special key!
... and
this guy is offering an Amazon gift certificate worth 10 times the amount paid on postage for sending him a postcard (squid flavour optional) from the underwater yuubinkyoku. No mention of the scuba expenses or risk of being eaten by giant octopi however...