
The deck was covered with iron spikes to discourage the enemy from attempting to board the ship.

Each was also equipped with a fully covered deck to protect against arrow fire, musket-shots, and incendiary weapons. Their most distinguishable feature was a dragon-shaped head at the bow (front) that could launch cannon fire or flames from the mouth. From their first appearance in the Battle of Sacheon, his turtle ships, equipped with at least five different types of cannon, greatly contributed to winning 16 times in 16 battles against the Japanese Navy until they were destroyed, under the command of Won Gyun, in the Battle of Chilcheollyang. Korean Admiral Yi Sun-sin, who won all battles against the Japanese Navy, is credited with designing the improved turtle ship. Turtle ships participated in the war against Japanese naval forces supporting Toyotomi Hideyoshi's attempts to conquer Korea from 1592 to 1598. However, these early turtle ships soon fell out of use as Korea's naval preparedness decreased during a long period of relative peace. The first references to older, first-generation turtle ships, known as gwiseon (귀선 龜船, Korean pronunciation: ), come from 14 records in the Annals of the Joseon Dynasty, which mention a mock battle between a gwiseon and a Japanese warship. One of a number of pre-industrial armoured ships developed in Europe and in East Asia, this design has been described by some as the first armored ship in the world. The ship's name derives from its protective shell-like covering.

It was used alongside the panokseon warships in the fight against invading Japanese naval ships.

A Geobukseon ( Korean: 거북선, Korean pronunciation: ), also known as turtle ship in western descriptions, was a type of large Korean warship that was used intermittently by the Royal Korean Navy during the Joseon dynasty from the early 15th century up until the 19th century.
