Thesmar Bay was a small bay located in the south-west of the Republic of Siddarmark, in the southern-portion of the South March Lands.  It was connected to Sandfish Bay on its east side, and the Swamp Neck on its west.  Thesmar City was found along its banks, where the Seridahn River met the Bay. (map)

In the Year of God 896, during the Civil War, it was a propossed landing site, and staging area for the Imperial Charisian Marines. (MTAT)