Heat the oven to 325 degrees and line two 13-by-18-inch sheet pans with parchment paper. In a large mixing bowl, stir together the oats, flour, coconut, granulated sugar and salt. Set aside.

Measure out your baking soda and keep it handy. In a medium saucepan over medium, heat the butter with the brown sugar, golden syrup and water, stirring occasionally, until the butter has completely melted and the mixture starts to lightly bubble. Immediately take the saucepan off the heat and add the baking soda. Stir for a few seconds, until the mixture expands to a blondish foam about twice its original volume.

Pour the foamy liquid over the flour mixture, scraping as much as you can from the pan. Mix just until the dry and wet ingredients are very evenly combined, then lightly press the dough into a mass at the bottom of the bowl. Let it rest for 5 minutes; this will make it easier to shape.

Scoop a couple tablespoons of dough and roll it between your hands to form a ball about 1 ½ inches in diameter; place on one of the parchment-lined pans. (If the dough is too crumbly to easily form balls, stir in some water, ½ teaspoon at a time, until it binds.) Repeat with the rest of the dough, spacing the balls 2 inches apart.

With your hand, flatten the dough balls slightly, then bake for 17 to 22 minutes, until light reddish golden brown (for chewier cookies) or deep amber (for crunchier cookies), depending on your preference. Let cool on a wire rack for at least 10 minutes.

Once completely cooled, store the cookies in an airtight container at room temperature for up to 5 days.