The containment procedures are solid but is missing a key detail of the anomaly. Nowhere in the conproc are the false distress messages of the anomaly mentioned beyond the "…intercept any communications originating from within the area." line. False messages would probably warrant more strict conproc on that aspect of the anomaly especially for would be rescue operations.
The physical description of the anomaly in the "RPC-XXX's hooks are pink…" paragraph are in need of polish. I do not feel much of the terror of the sea the anomaly should conjure from all things considered. I feel there is too much description and not enough telling like what is seen in the "RPC-XXX tends to target larger vessels when there are multiple ships in its effective area." paragraph.
The discovery and the Tethys discovery log are great addition to the article. The discovery of the anomaly from a folk tale along with it foreshadowing the Cetace's Kin involvement is a strong aspect of the article. However the interview still needs work. A more professional tone is needed from the Authority vessel, listen or read actual full length coast guard mayday/pan-pan calls for inspiration if you need it. I also like the implementation of the anomaly trying to draw more ships towards itself. However the explanation of the clandestine vessel's nature needs to be made more concise and to the point on both the authority and the vessels/RPCs side. The Tethys log is great all around, but the final description of the innards of the anomaly could use more detail. And finally, maybe change the "What is the Authority?" line as it sort of took me out of the scene.
The conclusion does its job at finally drawing it all together, the letter is a bit abrupt/shoehorned in the sense that they just found a letter by chance during a raid. However the letter itself is great and doesn't need to be touched.
Overall fair concept with fair execution, good sea monster, nothing too prophetic, a fair inclusion of a very situational GoI, and its not too politically harping but it may eventually become dated.
SPAGG and specifics:
Tuscany: Mayday! Mayday! This is the the SS Tuscany! We are sinking! We need a rescue immediately!
Improper prefix? SS stands for steam ship and is used rarely to designate modern vessels, Research Vessel (RV) would be a better prefix. Other usage of the prefix throughout the article could be reasoned as more plausible.
At this point, the distress signal is tracked to the exact coordinates the Tuscany gave, at the bottom of the Mexico basin. The Charybdis signals a possible anomaly to the Authority.
Sentence is a little hard to follow in its context.
Tuscany: We were looking for whale oil, but there aren't any whales around. Haven't There hasn't been for a long time.