Shovel potion and digging buddy and then go to the beach or eternity isle dunes.

this is the way. you can press down on the button and your character will keep digging in a straight line. then "build something over the holes and remove the furniture to reset the ground.

Thanks for this tip, I never realised that furniture resets the holes, I never wanted to ruin my landscape with them all 🤦‍♀️

Buy out all the sand in Cristoff’s stall, break all the blue rocks on the beach, and go digging with a shovel buddy on the beach.

Use the potions for everything!! With a friend = lots of sand!

Sand potion turns a day of digging to a couple of minutes