Keel-haul

A punishment said to have originated with the Dutch but adopted by other navies around the 15th and 16th centuries: A Line would be rigged from yardarm to yardarm Athwartships such that it passed under the ships Keel. The seaman to be punished would be secured to it (sometimes with iron or led weights About his legs) and be hauled up to one side. He would then be dropped suddenly into the sea, hauled underneath the Ship, and hoisted up on the other side. This would be repeated once he had recovered his breath.

While he was underwater this Ship would sometimes fire a large gun (cannon) "the which is done as well to astonish him so much the more with thunder of the shot, asto give warning unto all others of the fleet to look out and be wary by his harms" - Captain Nathaniel Boteler, ´A Dialogical Discourse´ 1634

Keel-hauling wained as a form of punishment in most navies at the beginning of the 18th centuary in favour of flogging with the cat-o-nine-tails.