Safety at Sea: All About Lighthouses

Written by: John Maguire

Lighthouses are structures that shine light beams to guide or warn mariners as they near or leave a harbor, and they're often seen while taking a boat cruise. Some lighthouses are quite tall: For instance, at 352 feet, Perry's Victory and International Peace Memorial at Put-in-Bay, Ohio, is the tallest structure to function as a lighthouse in America (though it was not originally built for this purpose). A lighthouse can be constructed out of concrete, steel, granite, limestone, iron, or brick.

The Purpose of Lighthouses

Before GPS, sailors relied on lighthouses for their safety. On a dark, cloudy night or in heavy fog, many dangers could lurk unseen for boats at sea. A watchman would be stationed atop the mast to look out for perils such as rocks, reefs, icebergs, or land, and lighthouses would help mariners to spot and avoid these hazards. They could also be used to help a boater determine where they were: Lighthouses that were built near each other would often be painted differently and flash their lights using different patterns to help mariners tell them apart from the water.

Lighthouses in History

In the earliest days, sailors could only look at the light from the craters of volcanoes to guide them to land. As architecture and engineering advanced, people began to build structures including lighthouses. One of the seven wonders of the ancient world, the Pharos of Alexandria was the earliest lighthouse. Located in Alexandria, Egypt, it was completed around 270 B.C., but it's not standing anymore. The oldest functional lighthouse, the Tower of Hercules in La Coruna, Spain, is 187 feet high and was built by the Romans in the second century.

Other notable lighthouses include the fifth-tallest in the world, the Lanterna, also known as the Lighthouse of Genoa. Found on the hill of San Benigno in Genoa, Italy, it has a height of 384 feet and was built between 1128 and 1161. Meanwhile, the most famous lighthouse in the United Kingdom, the Eddystone Lighthouse, has a different claim to fame: It's been destroyed three times since the first structure was built by Henry Winstanley in 1698, each time being rebuilt stronger than before. The first lighthouse on this site was a model for the building of modern lighthouses and the world's first to be built on the open ocean, perched atop a dangerous rock formation.

How Do Lighthouses Work?

The light from a lighthouse comes from its lamp. Nowadays, it's powered by electricity, but in earlier times, the light would have been created with firewood, candles, whale oil in an Argand lamp, or kerosene. From the turn of the 20th century to the 1960s, a Dalén light was used in many lighthouses. Equipped with a solar sensor, this acetylene-fueled light would be turned on automatically when darkness fell. Light from the lamp is focused with lenses so it can be seen from farther away, and a rotating mechanism makes the light flash when viewed from one place. In modern times, aerobeacons have been used in lighthouses because they are more cost-effective than traditional lights and lenses.

Towering Marvels

Historic lighthouses like the Tower of Hercules and the Lanterna are very popular with tourists. There's something romantic about a tall tower with a light at the top beaming warnings to sailors in the night. But perhaps the most famous "lighthouse" is the Statue of Liberty, which was originally constructed as both a work of art and a structure to help sailors navigate New York Harbor. From November 1886 to March 1902, the statue functioned as a navigational aid.

Visitors also flock to Les Eclaireurs Lighthouse, located at the southern tip of Argentina and known as "The Lighthouse at the End of the World." Completed in 1920, this 36-foot tower is flanked by the majestic mountains of the most southern point in the Patagonia region. Other famous lighthouses include the Cape Hatteras Light Station in North Carolina, Sweden's Kullen Lighthouse, Pigeon Point Light Station in Pescadero, California, and Peggy's Point Lighthouse in Peggy's Cove, Nova Scotia, Canada.