Bog snorkelling is a sporting event that consists of competitors completing two consecutive lengths of a 60-yard (55 m) water filled trench cut through a peat bog, in the shortest time possible.

Bog snorkelling is a sporting event that consists of competitors completing two consecutive lengths of a 60-yard (55 m) water filled trench cut through a peat bog, in the shortest time possible. Competitors must wear snorkels and flippers, and complete the course without using conventional swimming strokes, relying on flipper power alone. Wet suits are not compulsory, but are usually worn.

The sport of bog snorkelling was started in 1976 near Llanwrtyd Wells, Wales, United Kingdom. It began as a result of an over the bar conversation in The Neuadd Arms between Gordon Green and a few regulars.

The World Bog Snorkelling Championship, first held in 1985, takes place annually every August Bank Holiday at the dense Waen Rhydd peat bog, near Llanwrtyd Wells in mid Wales. It now attracts more than 200 entrants each year and is currently sponsored by Fun Swim Shop. The 2007 and 2008 events were not sponsored; the previous sponsor was London-based IT consultancy company SPMK in 2006. Dan Morgan of Brecon is the new world record holder with the time 1 minute 30.66 seconds, having shattered the previous record set by Joanne Pitchforth. Dan Morgan is the current men's champion, Dineka Maguire is the current women's champion, and John Hilliard the current champion junior bog snorkeller.

Other bog snorkelling events take place, particularly in Wales (but also in Australia, Ireland and Northern Ireland) including the associated mountain bike bog snorkelling (where competitors must ride through the bog on specially prepared mountain bikes), and the Bog Snorkelling Triathlon.