Cheap is a relative word when talking about the Bahamas. That being said, it's my experience that the least expensive airfares, are available by flying into Nassau. More flights, and more carriers servicing Nassau.
The mile is an English unit of length of linear measure equal to 5,280 feet, or 1,760 yards, and standardised as exactly 1,609.344 metres by international agreement in 1959.
That could mean 250 feet, 250 meters, or 250 fathoms. The scientist must provide the units for that value. It is also important to understand how to convert units from one unit to another. Most Americans know that 12 inches is equal to 1 foot, but it may not be known that 1 nautical mile is equal to 1.85 kilometers.