An Americanism, a swimming hole is designated as such by the choice and use of people, especially young ones, and in its literary appearances carries pastoral, idyllic, and melancholy associations. James Whitcomb Riley captures this in his poem “The Old Swimmin’ Hole”: “Oh! The old swimmin’ hole! In the happy days of yore/When I ust to lean above it on the old sickamore.” Swimming holes often have suitably evocative names— for example, Peekamoose Blue Hole in the Catskills, Cave Hole on the Potomac in West Virginia, and Grover Blue Hole on the Edisto River in South Carolina. These are places deep enough for swimming, and for dropping into from ropes suspended from tree limbs, and for diving from favorable positions on rock overhangs or the bank, and are customarily located on moving freshwater in the protected vicinity of a crook or bend. In “big water” and swift streams, the bounds of a swimming hole may be clearly marked by the eddy line, which is a surface expression of the eddy fence that separates the two circulation systems in three dimensions. On the far side of the eddy line, trouble awaits.