 Its seasonal campsite and activities for visitors and others living in and around Chelsea is Hargis Retreat which began in 1984.Chelsea is widely considered the fastest growing city in Shelby County, which is the fastest growing county in the state of Alabama.Chelsea is located near the central part of Shelby County at 33° 20' 24" N, -86° 37' 49" W (33.3401108 N, -86.6302625 W).