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Cheval's Grave is a location from The Legend of Zelda: Oracle of Ages. A cavern located beneath the grave of Cheval in Yoll Graveyard, Cheval's Grave serves as a "test" of sorts for those wishing to obtain Cheval's inventions, the Flippers and the Cheval Rope. The grave can only be entered with the help of Moosh. Inside the grave, Link must solve some puzzles before finding the Flippers. The Flippers must be used to obtain the Cheval Rope.
Interestingly, the cavern serves somewhat the same purpose as the Master Diver's cave test from The Legend of Zelda: Oracle of Seasons.
Spoiler warning: Spoilers end here.