House Sunderland is a noble house from the Vale sworn to House Arryn, although their hold over the Sunderlands is tenuous at best. They rule over The Sisters, a group of three islands located in the Bite. Each isle has a lord and all owe fealty to the Sunderlands
Long before Aegon's conquest the Sunderlands ruled the Sisters as pirates and petty kings until the Starks of Winterfell came down on them in what was called the rape of the Sisters. After bending the knee to the Arryns the subsequent war over the islands cost them most of their resources. Nowadays they are now known as a haunts for smugglers and dens of avarice.
The original seat of House Sunderland was destroyed during the rape of the Sisters some thousands of years ago. Their current residence built some time afterwards is a more meagre castle, stout and purposefully built.
Located on the eastern shore of Sweet-Sister, Wetwalls can only be accessed by land during low-tide, while at other times the sea acts as a natural moat and can only be reached by ship. The oceanic defence comes at the cost of a damp ridden exterior from which the castle gets its name and on the whole is seen as a dreary keep.