A few countries do not have an airport within their borders. These are typically small or microstates, often with limited space or close proximity to larger countries with accessible airports.

1. Vatican City The smallest country in the world, located within Rome, Italy. It has no airport, but it can be easily accessed via the airports in Rome.

2. Monaco This small principality on the French Riviera does not have its own airport. The nearest airport is in Nice, France.

3. San Marino Enclosed by Italy, San Marino has no airports. The closest airport is in Rimini, Italy.

4. Liechtenstein A small country between Switzerland and Austria. The nearest airport is in Zurich, Switzerland, or Friedrichshafen, Germany.

5. Andorra Located in the Pyrenees mountains between France and Spain, Andorra has no airport. The nearest airports are in Barcelona, Spain, and Toulouse, France.

These countries rely on neighboring countries' airports for air travel, with good road or rail connections to nearby airports.