In Scottish folklore, what blue-skinned sea fairies try to sink ships?

In Scottish folklore, the blue-skinned sea fairies that try to sink ships are the Blue Men of the Minch.

They inhabit the Minch, the waters between Scotland’s northwestern mainland and the northern Outer Hebrides. Folklore describes them as human-sized, blue-coloured spirits able to raise storms and attack passing vessels. They are also called storm kelpies, although ordinary kelpies are more commonly imagined as supernatural horses.

A famous story says their chief challenges a shipmaster with a two-line riddle or verse. If the sailor cannot complete it, the Blue Men attempt to overwhelm or capsize the ship. Their association with the dangerous tides near the Shiant Isles helped anchor the legend to a real maritime landscape.

The creatures are sometimes linked speculatively with Pictish painted people or with North African slaves brought by Vikings. Those are theories about the legend’s origin, not alternative names for the beings. The Minch is the distinctive clue separating them from Scotland’s broader kelpie traditions.