This is a trauma experienced by those unfamiliar with the wet ground conditions of certain parts of northern Europe, especially the peatlands of the west of Ireland. The trauma derives from a radical ambiguity in ground with a high moisture content, which offends the common distinction between water and dry land.
The distinction between the last two normally allows shorelines to operate as special sites of philosophical reflection and property speculation: Yeats's shores, Ballina's new waterfront apartments, etc. Bogdread arises where the distinction is threatened: what was viewed at first as a secure foundation now reveals itself as a quagmire.