Very good book, at every point of the story I kept wondering what would most likely happen next, sometimes I was right, and it still managed to surprise me.
The explanation is not farfetched and seems reasonable, but I am not completely satisfied with the ending.

Sammy/Hugo doesn't seem to feel anything? Gives me strong psychopath vibes...
Also, what happenes with the other passengers on the island? Do they sail to Amsterdam afterwards?
And I'm definitely not a fan of Sara's solution. I liked neither of the options, but don't have any better on my mind. Vigilante justice is not the right way. Creesjie and Sammy/Hugo shouldn't go without punishment.

I would be interested in the more horror endings Stuart Turton mentioned in the interview at the end of the audiobook.