Iron Cage

The Iron Cage is a specialized instrument of execution used by Conquistadan Empire authorities to punish those caught practicing piracy without the protection of a Letter of Marque. The process involves securing the condemned within a reinforced metal lattice and positioning it on the shoreline during low tide. As the tide inevitably rises, the prisoner is slowly submerged, leading to a public and agonizing death by drowning.

In some particularly cruel instances, the cage is positioned so that the water level only reaches the very top at high tide, forcing the victim into a state of perpetual exhaustion as they struggle to keep their head above the crest of each wave.

Beyond its role as a deterrent, the cage serves a practical purpose in the waters of Carrouban: the iron bars prevent Merfolk from scavenging the corpse, ensuring the remains stay as a grim warning to other passing vessels.

See: https://en.wikipedia.org/wiki/Gibbeting for the real-life analogue of this!