Located at a depth of 40m, the postbox in Layang-Layang Island is also considered the deepest underwater mailbox in the world.

Diving enthusiasts can send a letter to others with a waterproof postcard made of synthetic paper for RM10 (postage included) purchased at the resort and drop it in the underwater post box. The mails will be collected by the diver and dispatched by a MAS-Wings’ airplane to Kota Kinabalu City for delivery to the receivers’ addresses.

The postcards sent from Layang-Layang underwater post box will be stamped by a special hammerhead shark postmark, depicting the signature fish there, and with a Malaysia Book of Records sigil on the card. The post box also comes with a postcode 88005, a special number for this isolated Malaysian territory in South China Sea. Besides waterproof postcard, waterproof underwater case covers are available for keeping letters and other mail items dry.

According to mysabah.com

(https://www.mysabah.com/wordpress/underwater-post-box-sabah/)