Final answer:
Lake Vänern, the third-largest lake in Europe, is located in Sweden, which is the fourth-largest European country by area but has a relatively low population density.
Step-by-step explanation:
Lake Vänern is the largest lake in Sweden and the third-largest lake in Europe. This significant geographical feature contributes to Sweden's ranking as the fourth-largest country in Europe by physical area. Despite Sweden's large landmass, which exceeds that of the US state of California, its population density is quite low.
According to the 2017 census, Sweden had less than 10 million people, indicating a sparser population in comparison to other European countries.
Similarly, other countries in the region such as Finland, Norway, and Denmark also have populations of less than six million people each. Sweden's vast landscapes, of which Lake Vänern is a part, highlight the country's natural beauty and sparse population.