Between Dethry itself, and its far smaller neighbour: Little Dethry, lies a narrow isthmus of marshy land, known as the Trickle.
In the past, during the 18th and 19th centuries, the land bridge had been more substantial, having an average width of about 30 feet, and few places punctured with treacherous holes. In the late forties, the land seemed to submerge somewhat after a highly rare and localised earthquake, almost unheard of in the Outer Hebrides.
The Trickle now lived up to its name. It was at no point wider than 10 feet, the few patches of shingle or peat hags with overlying scrub offered little in the way of solidity. Towards its end, a mile or so from Little Dethry itself, the Trickle petered to a submerged trail at the peak of a sandbar that itself was located on a narrow rib of black volcanic rock. Patches of quicksand and deep potholes lurked at either side. The water became very deep very quickly if you strayed far from this narrow walkway.
The whole experience of crossing to the smaller Isle became a highly unnerving experience, with the optical effect created near the trail's end making one feel as if he were negotiating a heinously narrow bridge of sludge straddling black abyssal seas either side.
However, over the preceding centuries, "threading the Trickle" had become something of a Rite of Passage for teenagers in the area, which here, unusually perhaps, included both sexes.