Ten thousand years or so after the first humans built sailing ships for trade, the coast still matters immensely. In fact, there are only two prosperous landlocked countries of any size: Austria and Switzerland.
Read the whole thing.
Paul Collier, in The Bottom Billion, emphasizes that being landlocked is a real handicap.
Think about how important the Erie Canal was. Or the Suez Canal. Or the Panama Canal. Try to name a city that was important in 1830 (i.e., before railroads) that is not located on a major river.