Dem Der Rocks (frequently misinterpreted as Dender Rocks) are a group of rocks guarded by Lillie Lightship. She makes sure all vessels can see them clearly with her light. In Regatta, Lillie was involved in a collision with a ship near these rocks, which pierced her side and let water into her controls, and her light went out. The tramp steamer was out of control and went straight into the rocks, it then sunk slowly into the sea. The area is also the home to red and white marker buoys, as seen in Jinxed.