That Sinking Feeling

From publisher blurb:

For a level 9 party!

When the trade galley Fairmorning fails to make it in to port, it’s up to the PCs to investigate. When their search leads them to the depths of the seafloor and a mysterious underwater shrine, more questions arise than answers!

A collective of sahuagin barons, led by their matron Mes’Dal’Umbrak (Sahuagin for “Mother-of-the-Deathly-Tide”) is using the shrine to concoct something evil and twisted in the deep. The party (with a little help from the concerned merfolk) must defeat the sahuagin forces to keep the seas safe… but sooner or that sinking feeling sets in - there's something much more evil at hand!