Tryal Rocks, sometimes spelled Trial Rocks or Tryall Rocks, formerly known as Ritchie's Reef or Greyhound's Shoal, is a reef of rock located in the Indian Ocean off the northwest coast of Australia, 14 kilometres (8.7 mi) northwest of the outer edge of the Montebello Islands group. It is named for the Tryall, the first known shipwreck in Australian waters, which sank after striking the then-uncharted rocks in 1622. Described as "the theme and dread of every voyager to the eastern islands", their location was sought by mariners for over three centuries before finally being determined in 1969.