Calais
Calais ( , traditionally ; ] ; Picard: "Calés" ; Dutch: "Kales" ) is a town and major ferry port in northern France in the department of Pas-de-Calais, of which it is a sub-prefecture.
 Although Calais is by far the largest city in Pas-de-Calais, the department's prefecture is its third-largest city of Arras.
 The population of the metropolitan area at the 2010 census was 126,395.
 Calais overlooks the Strait of Dover, the narrowest point in the English Channel, which is only 34 km wide here, and is the closest French town to England.
 The White Cliffs of Dover can easily be seen on a clear day from Calais.
 Calais is a major port for ferries between France and England, and since 1994, the Channel Tunnel has linked nearby Coquelles to Folkestone by rail.
Canton of Calais-3
The canton of Calais-3 is an administrative division of the Pas-de-Calais department, in northern France.
 It was created at the French canton reorganisation which came into effect in March 2015.
 Its seat is in Calais.
Canton of Hénin-Beaumont-1
The canton of Hénin-Beaumont-1 is an administrative division of the Pas-de-Calais department, in northern France.
 It was created at the French canton reorganisation which came into effect in March 2015.
 Its seat is in Hénin-Beaumont.
Dover
Dover ( ; French: "Douvres" ) is a town and major ferry port in the home county of Kent, in South East England.
 It faces France across the strait of Dover, the narrowest part of the English Channel, and lies south-east of Canterbury; east of Kent's county town Maidstone; and north-east along the coastline from Dungeness and Hastings.
 The town is the administrative centre of the Dover District and home of the Dover Calais ferry through the Port of Dover.
 The surrounding chalk cliffs are known as the White Cliffs of Dover.
Canton of Calais-1
The canton of Calais-1 is an administrative division of the Pas-de-Calais department, in northern France.
 It was created at the French canton reorganisation which came into effect in March 2015.
 Its seat is in Calais.
Canton of Calais-2
The canton of Calais-2 is an administrative division of the Pas-de-Calais department, in northern France.
 It was created at the French canton reorganisation which came into effect in March 2015.
 Its seat is in Calais.
Port of Calais
The Port of Calais is a port in Calais, northern France.
 The port is the fourth largest port in France and the largest for passenger traffic.
 It accounts for more than a third of economic activity in the town of Calais.
Canton of Hénin-Beaumont-2
The canton of Hénin-Beaumont-2 is an administrative division of the Pas-de-Calais department, in northern France.
 It was created at the French canton reorganisation which came into effect in March 2015.
 Its seat is in Hénin-Beaumont.
Boulogne-sur-Mer
Boulogne-sur-Mer (] , Latin: "Gesoriacum" or "Bononia", Dutch: "Bonen" ), often called Boulogne ( ), is a city in Northern France.
 It is a sub-prefecture of the department of Pas-de-Calais.
 Boulogne lies on the Côte d'Opale, a tourist coast on the English Channel, and is the most-visited location in its region after the Lille conurbation.
 Boulogne is its department's second-largest city after Calais, and the 60th largest in France.
 It is also the country's largest fishing port, specialising in herring.

Question: Calais ( , traditionally ; ] ; Picard: "Calés" ; Dutch: "Kales" ) is a town and major ferry port in northern France in the department of Pas-de-Calais, of which administrative division of a country that is below prefecture or province?
Answer: Subprefecture