Because of its unusual geography, Niuafo'ou used unconventional means to receive its postal communications known as "Tin Can Mail."
I managed to pick up a few of these in the past for SC members. Here's one I discovered yesterday.

The Tale of Tin Can Mail. - When copra traders set up operations on the island near the turn of the century, a method of communications became necessary.
At one time passing steamers would seal incoming mail for the island in ship's 40-pound biscuit tins which were then thrown overboard to native swimmers. The swimmers had maneuvered a mile or more through the turgid surf, towing the outgoing mail that had been carefully soldered in tins. The swimmers and ship would exchange mail containers and each would be on their way. From this unique method of mail delivery, the island became known as Tin Can Island and the letters carried thus are called Tin Can Mail.
In 1983, an airstrip was completed eliminating the need for Tin Can Mail.