That… is a very weird and very silly book.
It’s got a frame story of one Wally Warmbottom. He’s shipwrecked on an island far from anything–but luckily, he’s got lots of paper and bottles to send out letters.
And some of those bottles have other stories in them. Such as the titular mooses and bazookas. And another about rocket(s). And a few others.
It reminds me of On the Edge of the Dark Sea of Darkness, with the same overwritten funny because it’s saying the same thing a bunch of times in a row sort of humor.
It gets old.
Or perhaps I got old.
My son seemed to enjoy it well enough though.