Message from the bottom of the river

Exploration Stage: Dragon Sailboat
From: Valerie
Description: Martha was able to conjure up a vision of a river city and communicate with the emperor there. Being separated by a body of water made it difficult to establish a firm spiritual connection, but the emperor promised to send a message to the earth. Let's look for it!
Completed: Thanks for finding my message! I was expecting a paper letter to arrive, but it would get wet. It's impossible to write with ink underwater. Oh, you've already finished deciphering it? Martha, you are a genius! The emperor is offering to trade our artifact for the treasure? So we are coveting each other's artifacts!