Preheat oven to 350°.
Line the bottom of a springform pan with parchment paper. Lightly grease the sides of the springform. Set aside.
In a medium bowl, whisk together cake mix, eggs, oil, milk, water, lemon zest, and lemon peel (if using) for two minutes.
In the bottom of the springform pan, add the blueberries. Sprinkle with sugar and coarse salt (if using).
Top blueberries with the cake mix. Spread evenly so all berries are covered. Place springform on a baking sheet and place in the oven to bake for 40 minutes.
After 40 minutes, using a toothpick, check the center of the cake. The toothpick should come out clean with only a few small crumbs.
Remove cake from oven and allow it to cool. Release the springform pan and remove the outer ring. Place a plate on the cake and flip it so the blueberries are on the top. Remove the parchment liner.
Cover if not serving right away. When ready to serve, dust with powdered sugar. Cut into slices and serve.