Atlantis Codex

Atlantis lies on a world given over almost wholly to the sea. Its people raised their city on the reefs stone by stone, and when the waters rose they did not leave. They sealed their halls and built downward instead, each generation a little deeper than the last.

This copy was scribed in the Arcanum library from the last letters to reach us, before the silence.

Atlantis speaks on the Ocean Frequency, which carries through water as a bell carries through air. Any shell that grew in the sea rings to it, which is why their relays are built about a clam set in a ring of stone.

Their towers answer in turn, as their keepers gave them to us:
The Tide Gate, low and slow.
The Coral Spire, three notes rising.
The Deep Hall, a hum too low to hear, felt in the stones.

In their last letters the Atlanteans wrote of something in the deep that had begun to answer their bells. They built the jammer to stop up their world, so that whatever it was could not follow a signal out.

The final letter is short. "Do not call to us. We will call when it is safe."