The original Hans Christian Andersen fairy tale The Little Mermaid takes place in a fictional underwater kingdom and a nearby human coastal kingdom that is usually understood as a romanticized, imaginary version of 19th‑century Denmark or a similar northern European coast.

Core setting in the Andersen story

  • The mermaid lives in an underwater kingdom at the bottom of the sea, in the Sea King’s coral and amber palace, with her father, grandmother, and sisters.
  • The human world is represented by the prince’s seaside palace , a coastal kingdom with ships, churches, and European‑style architecture, suggesting a northern European setting inspired by Denmark, where Andersen wrote and published the tale in 1837.

Time and place details

  • The story is generally placed in the mid‑1800s , matching Andersen’s own era, though the text never gives a precise year.
  • Geographically, the action happens in and above the sea near a European coastline , with references to church spires, ships, and Christian beliefs that align with 19th‑century Danish (or similar European) culture.

If you meant the Disney versions

If you were thinking of Disney’s The Little Mermaid rather than the original tale:

  • The 1989 animated film uses a vaguely European seaside kingdom without naming a country, but fans and some commentators often link its look to Mediterranean or European coastal regions.
  • The 2023 live‑action remake explicitly reimagines Eric’s island kingdom with a Caribbean vibe, maps, and town culture that place it in a warmer, tropical island setting.

So, in short: the classic story is set in a fictional underwater realm and an unnamed European coastal kingdom inspired by Andersen’s Denmark, while newer screen versions shift the human kingdom’s look, with the 2023 film moving it to a Caribbean‑style island world.