Every August bank holiday in Llanwrtyd Wells, Wales, competitors in masks, snorkels and flippers plunge into a 60-yard trench cut through the Waen Rhydd peat bog and race two lengths using flipper power alone. This episode lays out the rules, the acidic, freezing, near-opaque water, and the biomechanics of why banning arm strokes turns 120 yards of mud into a relentless anaerobic test of the legs and core.

The conversation traces the sport from a 1976 pub conversation to the 1988 founding of the World Bog Snorkelling Championship, the international field that now flies in from Australia to South Korea, and the charitable model run by Green Events that has supported the Cystic Fibrosis Trust and the Motor Neurone Association in memory of treasurer Ron Skilton. It also covers the 2019 Royal Mail stamp honoring the event alongside cheese rolli ...