Human fascination extends beyond exploring the space above us; we have always been equally intrigued by the mysterious depths of our vast ocean. Despite venturing into the far reaches of outer space before delving into the vast depths of our own ocean backyard, underwater exploration has achieved significant milestones through the development of functional submersibles. These remarkable vessels have enabled us to uncover the mysteries hidden beneath that dark, inhospitable liquid abyss that blankets our planet.

Throughout history, these silent guardians of the deep have undergone a remarkable evolution, evolving from basic submersible crafts to formidable war machines. In this article, we trace the origins of these vessels, from their seemingly impossible conception to their pivotal role in shaping the history of naval warfare.

Dating Back to da Vinci

Historians suggest that the concept of underwater crafts can be traced back to the late 1400s when the renowned Italian Renaissance artist and inventor Leonardo da Vinci claimed to have discovered a method to submerge a ship for an extended period. However, da Vinci kept his discovery a secret due to fears that it could be misused by assassins, who were prevalent during that time. It is worth noting that even before da Vinci’s undisclosed blueprint for a functional submersible, the idea of utilizing underwater vessels for combat purposes had ancient origins.

The first practical submersible took a couple more centuries to move beyond the conceptual phase and into actual construction. However, despite the potential shown by the leather-covered, 12-oar rowboat, its viability was eventually dismissed by the Royal Navy during the development process.

A reconstructed model of the Drebbel wooden submarine by British boatbuilder Mark Edwards, 2002. (Image source: Wikimedia Commons)

On the other hand, America built its first military submarine in the mid-18th century, aptly named the Turtle. Designed by inventor David Bushnell, the one-person submersible vessel has a compact structure of about 6 feet (1.8 meters) in length and 3 feet (0.9 meters) in height and was made of wood and metal. It was much like an aquatic bicycle, its propulsion powered by a hand-cranked propeller allowing the craft to move on the surface and underwater. It also featured a ballast tank that could be flooded with water to submerge the vessel or pumped out to resurface.

One of the most distinctive aspects of the Turtle was its attack mechanism—a large screw-like device attached to the front. During operations, the operator would approach the target ship, drill into its hull using the screw, and attach a mine fitted with a timer. Reportedly, the Turtle’s first notable mission occurred in 1776, during the Battle of New York, intending to attack the British warship HMS Eagle. Even though the mission would be unsuccessful, it marked the first use of submarines for combat—and the development just took off from there.

Trial and Error

In the early 19th century, renowned inventor Robert Fulton introduced the Nautilus, a remarkable vessel that is often hailed as the first practical submarine. Although it relied on human power and lacked combat capabilities, similar to the Turtle, the Nautilus laid the groundwork for future advancements in submarine design. Despite being considered experimental and unsafe for combat, submarines of this era played a role in the American Civil War.

Among these experimental underwater crafts was the Confederate H.L. Hunley, named after its primary benefactor Horace L. Hunley. Measuring nearly 40 feet (12 meters) in length, this vessel was operated by a small crew of eight men who used a crank mechanism to propel it forward. Despite its limitations, the H.L. Hunley bravely participated in the chaotic naval warfare against Union forces, exemplifying the pioneering spirit of submarine exploration during that time.