Answer:
Finland
Explanation:
Out of the numerous countries that are members of the European Union, Finland is the one with the smallest population density. The country is relatively large for European standards, but it has very small population. The population density of this Northern European nation is 16 people per square kilometer, which is far beyond the average for the European Union. The reason for this is mostly the climate. Finland is one of the coldest countries in the world. Big portion of the country has very harsh conditions for living, so naturally the people don't live in those areas. Also, the lakes are occupying lot of the territory of this country, thus reducing the area where the living conditions are bearable. Most of the population lives in the southern part of the country, being either along the coastline, or very close to it.
These subs are useful in studying the ocean floor, where it is so deep that divers would be crushed by the water pressure. For example, research submersibles are used to study shipwrecks like the RMS Titanic.
