Where the land meets the ocean, with plenty of water and a large landmass for battles by land or sea.
Coastal is difficult to play, and can be unfair to one player. This map is an in-between map; there is a lot of land, but water can make or break the game. In some games, one player will be stuck with a small lake (small amount of water, and little fish), and the other player will have a big open ocean, abundant with fish. Scouting is extremely important on this map; you will need to decide quickly if you are going to fight on land or water.
Walling: Walling can be difficult on Coastal. Even if you have a wide-open land, it is still a good idea to wall choke-points and use buildings to narrow the large gaps.
Housing Coastlines: This is using your dock builders to build houses all the way down the coastline. Not only does this satisfy population needs, but it also serves as great radar for landings. This should be done on every water map, and even on land too.
Patrol Trick: This is a must on water. You need to keep your boats on Patrol. They attack sooner once seeing an enemy and groups of boats attack.
Grush: Grushing is possible, but walling can be difficult due to the large amount of land you'll have to wall. If you have the good part of the water, grushing is definitely worthwhile; but if you have poor water, grushing is not as important.
Flush/Fast Castle: Fighting on land initially is a strong strategy on Coastal, especially if you have the weak water. You will need to make a strong impact, because you will have a weaker economy. If the surrounding land is unwallable, you will want to Flush or Fast Castle, powered by a dock and some Fishing Boats.
Credit to: aok.heavengames.com