Vanishing island

Vanishing island refers to any permanent island which is exposed at low tide but is submersed at high tide.

Vanishing islands occur globally.

[1] In early times, seamen were confused by this phenomenon and invented explanations for it, usually involving a massive sea monster that would let a crew land on its back before submersing itself, drowning the crew.

Notable examples of these include the aspidochelone, Fastitocalon, Jasconius, Lyngbakr, Hafgufa, and various accounts of the kraken.

[2] The phrase is sometimes incorrectly used to refer to Islands which may be permanently lost due to climate change.