Fantasy, fable, fever dream - you choose
Having not read the juggernaut that was Mark Haddon's 'The Curious Incident of the Dog in the Night-Time', I came to this novel completely unaware of his style.
What a joy to read the work of such a gifted author who weaves tales and twists out of innocuous beginnings and shocks you to the core with the simplest of sentences.
'The Porpoise' is not the easiest of reads due to its structure and is best read consistently and expeditiously to keep all the threads bouncing along vibrantly in your brain.
And how it pays off, with scenes and circumstance to enjoy and wonder over for years to come.
It is not perfect; as the author says in his own thanks, there are mistakes. This makes it fit even more as a fantasy, fable or fever dream and perhaps more likeable as a result.
When you read such writing, it makes a reader revel in the imagination and wordskill of another, if you can go with it. If you can't then I'm afraid you're missing out on one of fiction's golden adventures.