SCP Foundation

https://www.dropbox.com/s/w2rfrictfa5knaa/Untitled-min.png?dl=0

My idea here is an entity encountered in Florida, USA, escaped the Foundation in the early 2000s, and despite reports from eyewitnesses/coastguards randomly across the world, has not been seen by them again since.

Its a living ship - from its behavior, either a sentient vessel that thinks its a bottle-nose Dolphin, or a ghostly Dolphin that thinks its a passenger cruise ship. Almost as if its two things merged, or in a state of flux. A modern day Flying Dutchman…

MTFs sent to investigate, boarded the creature, reporting the passengers were all very friendly and accommodating, but curiously circulating round the decks while wearing red. The ship's crew all wore white uniforms or overalls. As time passed, the crew begins to swarm round/challenge them for their boarding passes, which the passengers freely offer them.

Ordered to refuse and withdraw for fear of the MTF's safety - radio communication with them is suddenly jammed out. The once affable crew are now hostile, savagely attacking the MTF and hunting down the teams. The crew devouring them like zombies. Over the next hour or so, the men's numbers dwindle and there's a desperate struggle from the survivors to escape this living dolphin ship.

No exit in sight, some in fear of being killed, accept the gracious invitation however, and make strange reports over the radio intercom they are now enjoying their "well-deserved vacation" across the globe.

Having consumed, or assimilated the remaining soldiers, the entity then vanishes from detection…

You seem to have 2 ideas here which seem very loosely connected.

Its a living ship - from its behavior, either a sentient vessel that thinks its a bottle-nose Dolphin, or a ghostly Dolphin that thinks its a passenger cruise ship.

I'll be honest, this got my attention as I could see some potential here but then:

The once affable crew are now hostile, savagely attacking the MTF and hunting down the teams. The crew devouring them like zombies.

This seems completely unrelated to the original idea and is completely boring in comparison. I could see some potential in a cruise ship that thinks it's a dolphin and somehow is able to submerge, surface and potentially jump through a very large hoop but the idea of the crew and them being hostile and everything is cliché and seems completely unrelated.

A better idea would've been that the crew and passengers are all dead because this cruise ship thinks it's a dolphin and submerged or maybe it also tried to save the passengers but because it doesn't realise its size, it kind of crushed all of them.

Either way, the potential of the idea would be around the part where the ship thinks it's a dolphin, the crew being hostile and killing people should really be taken out completely.

Oh, also:

the passengers were all very friendly and accommodating, but curiously circulating round the decks while wearing red. The ship's crew all wore white uniforms or overalls.

Is this meant to be red blood cells and white blood cells? If it is, it's way too obvious.