Sea Is Not Made of Water

The author built three tidepools in western Scotland and studied the plants and animals that occupied them. This is a natural history book, but although it starts in the expected way describing prawns and green crabs, it expands to describe the history of the discovery of the origin of the tides, the human history of western Scotland, the philosophy of Heraclitus, Martin Heidegger, and more. He sometimes writes a little elliptically.
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Note that my copy of this book is not titled this way. It's just Life Between the Tides.