Greece is not too crowded other than Athens and Thessaloniki, these two cities have 3M and close to 1M in population, which add up to about 40% of the population of the entire country. So, that is why once you get away from Athens, you are in another world, a much freer and tranquil way of life. Time is slow and with the Mediterranean sea and surf, you can just take it easy.
From @sunray