Like Marching Army Ants

. . . but actually it is the annual Black Rock Race.  Seven kilometres in total, five across the sands passing around the rocks in the top-left.  It takes place every May or early June whenever a suitable tide coincides with a Friday evening.

It starts in the Fife village of Kinghorn and between 1000 and 1200 competitors take part.

Before it starts, there is a shorter road-race for local children of primary school age.  That was proudly won by my great grandson. (see extra)