In a medium bowl, stir together the water, yeast, and honey to dissolve.

In a very large bowl, whisk the flour and salt together, then add the water-honey-yeast mixture and the olive oil.  Stir with a rubber spatula until it's just incorporated, then scrape the sides of the bowl clean.  It will be rough and shaggy but that's totally fine.

Cover with plastic wrap and leave out at room temperature to ferment for 12 to 14 hours, until at least doubled in volume. I do it overnight.

Once it's risen, get an 18-by-13 inch rimmed baking sheet and spread 2 to 3 tablespoons of olive oil onto it.

Use a spatula or your hand to gently release the dough from the sides of the bowl and fold it onto itself gently, then pour it onto pan. Pour an additional 2 tablespoons of olive oil over the dough, and use your hand to spread it across the dough. 

Slowly and gently stretch the dough to the edges of the baking sheet by placing your hands underneath and pulling outward.  The dough will continue to shrink a bit, so repeat the stretching once or twice over the course of 30 minutes to ensure the dough remains stretched.

At the end of the 30 minutes, "dimple" the dough by pressing the pads of your first three fingers in at an angle (don't push all the way through the dough).

Make the brine by stirring together the salt and water until salt is dissolved, then pour it over the dough to fill the dimples. It will seem too wet but just go with it!

Set the focaccia aside to rise for 45 minutes until the dough is light and bubbly.

With 15 minutes left in that final rise, adjust your main oven rack to center position, and a second rack to the upper position. Preheat oven to 450°F.  If you have a baking stone, put it on the center rack, and otherwise invert another sturdy baking sheet and place it on that rack. Allow it to preheat with the oven until it's very hot, before proceeding with baking.

Sprinkle the dough with flaky salt and bake for 25 to 30 minutes directly on top of the stone or inverted baking sheet, until the bottom crust is crisp and golden brown when checked with a metal spatula. To finish browning the top crust, move the focaccia to the upper rack and bake for 5 to 7 minutes more.

Remove from the oven and brush or douse with 2 to 3 more tablespoons of oil over the whole surface (don’t worry if the olive pools in pockets, it will absorb as it sits). Let cool for 5 minutes, then release the focaccia from the pan with a metal spatula and transfer to a cooling rack. Let it cool for at least 30 minutes! 

Serve warm or at room temperature.