Walking the plank might not be the most pleasant of deaths, but it seems moderately more humane than the other favored maritime punishment of keelhauling.
A punishment that often ended in death due to the severity of the wounds sustained (or was simply carried out until the point of death), it saw the victim, legs weighted and suspended from a rope, dropped from the bow of the ship and then rapidly pulled underwater along the length of the hull — and over the keel (the beam that runs longitudinally down the center of the underside of the ship), hence the name — to the stern.
In the age of wooden sailing ships, the hull of a vessel would normally be coated in a thick layer of barnacles, whose shells could be rock hard and razor sharp.
As the drowning sailor was yanked relentlessly through the salt water, these protrusions would strip the skin from his body, gouging out raw chunks of flesh and even, by some accounts, tearing off whole limbs or severing the head.
If the sailor was still alive, they might be hung from the mast for 15 minutes before going in again. In some cases, the victim would have an oil-soaked sponge — containing a breath of air — stuffed into their mouth to prevent a “merciful” drowning.
Employed mostly by the Dutch and the French from the 1500s until it was abolished in 1853, accounts of its use date back as far as Greece in 800 B.C.