I think this would be really cool, it could be another version of the Kraken, it would look like the mythological creature. If it eats you, you You are screwed any you die and you ship would be destroyed. What you need to do is use a scuba suit (which im sure people have shown in the past) to go below and hit it on its weak spot under water. The charybdis has tentacles too these tentacles could try to keep you away from its weak spot so before you go below you have to shoot down tentacles with cannons. To trigger this event you would need to start a tale like the mission or it could be random like the Kraken, except the Kraken would avoid galleons and the Charybdis would only go for galleons.
Adding a new Monster boss called Charybdis based on Greek mythology
looks cool
my monster(s) idea where see serpens with a celtic style
take a look at the sea serpents if you will (sadly no artwork)https://www.seaofthieves.com/forum/topic/92793/ideas-for-sea-of-thieves/4
2 su 3