It starts off with a fun hook, find the daughter who has been missing for 100 years! I think the initial investigation phase is generally good.
The plot is inconsistent and weakly connected from there:
- Can't cast water breathing? Adventure fails.
- Why doesn't this module have a sidebar regarding underwater combat and the constitution saving throws required of long term exploration in the chilly high pressure depths?
- Head into the ship before talking to the merfolk? Adventure fails because you don't know how to save the only creature that can unravel the mystery.
- Why are merfolk warlocks pact of the fiend? It's a completely thoughtless choice.
- Aremag doesn't have legendary actions? Aremag is literally a legendary named denizen of the Bay of Chult, but his stat block is so boring as a solo opponent for a T3 party that I simply can't continue on the subject and remain civil.
- Aremag's motivation and scripted behavior regarding Dalnira and his lair is nonsensical.
- There isn't enough time in a 4 hour block to run the Order of the Gauntlet mission.
Many aspect of the module are solid. The underwater settings are pretty well detailed for encounter purposes. However, the monster generator on the ship is problematic for encounter length as it keeps adding fairly low threat monsters.
There are too many ways to fail this before you start by not having the right party. Too many ways to fail in game due to making reasonable choices based on available information. Too many creature design/selection flaws for the fights to make sense for the underwater milieu.
[2 of 5 Stars!]