- Base yield: +1 Food and +1 Gold
- Provides Fresh Water to nearby tiles
- Allows construction of Harbor Districts
- Allows sea travel before researching Cartography
Compared to earlier Civilization games, coast tiles are less useful. The Harbor means a City Center can be further inland, and coast tiles do not provide much when worked unless a sea resource is present. As such, it's generally best to avoid settling with too many sea tiles in the city radius.
Of course, coast tiles are the only place where early ships may move before researching Cartography. Thus, a nation which extends its territory to cover all coast in a certain location will effectively block all maritime movement there in the early game for all nations who don't have Open Borders with this nation! This may often have great strategical importance.
Note that some Wonders can only be built on the coastline, often next to a Harbor.
Coastal waters (unless, of course, it's a lake) beckoned early civilizations to venture out from land, where they found all sorts of riches and good things to eat. Thus, for millennia men had no need (or feared) to sail out of sight of land.