Principality of Hutt River is a tiny sovereign nation within Australia. It seceded in the 1970's after a dispute over wheat quotas. Located on a large farming property 517 km north of Perth, near the town of Northampton, this country has its own currency, stamps and they even provide entry visas to visitors who want to visit this tiny nation.
The principality was founded on April 21, 1970 by Leonard George Casley (born August 28, 1925), when he and his associates proclaimed their secession from the state of Western Australia. It has an area of 75 square km (29 sq mi), making it larger than several independent countries. It is not recognized as a country by the Australian Government or any other national government, and the High Court of Australia and Supreme Court of Western Australia have rejected submissions arguing that it is not subject to Australian laws.
Here's an interesting video on the history of this nation.
Well, would you call a self-sovereign piece of land a country, if no other country in the world recognizes it?
I wouldn't, but that's what it has been operating for almost half a century. It has its own passport, postal service, money and visa system that whoever enters complies with. May be it will take another 50 years to get recognized by other nations. :)