Hello! First off I love the vibes of the pamphlet, it looks fantastic, it has a great sense of humor and it seems like it would be pretty easy to sit down and play. Great job!
The only real critiques I have are;
1. I think while the statblocks have great info on the characters I think a little more could have been added mechanically, especially a combat score and damage they deal.
2. The theme of "under the surface" was a little lacking, other than the adventure taking place at a sea-world equivalent.
3. While I love the flavor of the introduction being in universe I think the adventure could have used a little more setup information. How long has it been since the creature got loose, what exactly the PCs are doing here, maybe a little more background on the station itself.
Other than those small critiques I think this is a great adventure and one I'm definitely interested in running. Great job!