The Trent Aegir is a tidal bore on the River Trent, perhaps named for the Ægir, a personification of the ocean in Norse mythology. It tends to run out of steam just south of Gainsborough. The town was briefly the capital of Viking England, and stories abound that this is where King Cnut attempted to turn the tide (or demonstrated that he could not).

Polly Howat, in Ghosts and Legends of Lincolnshire and the Fen County (1992), buys wholly into this longstanding myth, and Derek Turner mentions it in Edge of England (2022). There is, of course, no evidence whatsoever to support this, and in fact it seems wholly unlikely: a tidal bore is essentially one long wave, not a rising tide, so would have been far less effective at proving the point it is said Cnut was making.

In George Eliot’s classic novel The Mill on the Floss (1860), St. Ogg’s is modelled on Gainsborough, and the novel makes reference to the Aegir, which ‘takes its name from the Danish god Oegir’.

It used to be common to throw coins or silver into the Aegir, especially at high tides (i.e. around the equinoxes), to ward off evil or prevent drowning in the Trent. Maureen Sutton, in A Lincolnshire Calendar (1997), suggests this might be linked to pre-Christian rituals, and also wonders whether the name might simply be a bastardisation of ‘ogre’, though she provides no evidence to back up the speculation. Food for thought, perhaps.

The Aegir a fascinating phenomenon, and worth observing. There is a timetable for the Trent Aegir here.

Words by RORY WATERMAN