海壇島，位處福建省福州府的外海，是福州省城南面海上的門戶。海壇遊兵，設立目的在鞏固省城的南面藩籬，並填補內遷後南日水賽所遺留的海防空隙，扮演昔時水賽設在近海島中「據險伺敵」的角色，而它的母港基地曾數度地遷移地點──即明隆慶時初設在鎮東衛城，至萬曆中期西遷至海壇島上，之後又回遷鎮東衛，崇禎時又再北遷至松下鎮，它的整個的過程，在時間上幾乎跨越明代的中後期，前後長達七十年之久。海壇遊兵，是觀察明代中後期福建海防變遷過程的──面鏡子，吾人可透過海壇遊兵母港基地數度遷移的過程，去認識福建地方當局海防決策的取向，以及當時官方民心的變化經過。

The location of Haitan Island is in the sea in Fuzhou of Fujian Province. The purpose to set up the fleet of Haitan is to protect Fuzhou. In addition, after removing in order to fill in the naval base of Nanjih too, the defence space left over. The base of the fleet of Haitan is originally set up in Chentungwei. Later, move to Haitan Island first, and then move to Chentungwei. Move to Sunghsiachen afterwards. Through above-mentioned course of moving ,can know the direction of the coast defence policy in Fujian of Ming Dynasty .