Can be found here: https://joshscotland.com/thrill-digger-assistant/

Thrill Digger Assistant

Thrill Digger is a minigame in The Legend of Zelda: The Skyward Sword where you dig up as many rupees as possible! If you dig up a bomb, it's game over. The minigame is similar to Minesweeper. You can play by heading to the Eldin Volcano area and speaking to Tubert.