The Lost Ruins den consists an underwater structure that is divided into two floors. The structure is made of light blue marble and appears to have an Ancient Greek style of architecture. Most of the lower section's floor tiles are broken. Tall seaweed can be seen swaying in the background of the den.
- It is the second and most expensive Underwater Den, following the Sunken Ship.
- The Atlantis Party has a very similar appearance, but the layout is flipped horizontally.