Technically, starting from the ocean, you have the tidewater on the Eastern shore, then the coastal plain from the western shores of the Bay until you hit the piedmont, also referred to as the fall line, that continues until you reach the first ridge, the mountains. Also, some do include the tidewater and coastal plain as part of the coastal plain arguing that the Bay is just a body of water that intruded into the coastal plain after the ocean receeded.
My recollection from a college geography class when the Bee Gees were #1 in the charts, was that the area inclusive of the tidewater and coastal plain were, at one time, under the/an ocean.