They guide ships safely into harbor at night and during storms, but lighthouses serve an important role beyond navigation. "Lighthouses serve to remind us that our nation was built on maritime commerce," lighthouse historian Jeremy D'Entremont told Weather.com. "Without lighthouses, you could not have had the safe movement of that commerce. They also remind us of the lighthouse keepers and families that lived at these locations in the past, devoting themselves to 'keeping a good light' no matter what the weather conditions are."

But the lights are permanently out at some of the world's lighthouses, whether they were abandoned due to natural disasters or decommissioned due to technological advances or newer structures. Here, we tour 9 of the world's abandoned lighthouses—eerie (some are believed to be haunted), forgotten sentinels of the sea.

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1. Rubjerg-Knude Lighthouse, Denmark

In northern Denmark, on the coast of the North Sea in Rubjerg, there is an abandoned lighthouse that is being swallowed up by shifting sands. When the lighthouse was first built in 1900 , it was located over 655 feet inland on the coastal slope’s highest point, with no large sand dunes nearby, according to the monument’s official website. Since then, however, wind from the North Sea has steadily blasted the cliffs near the lighthouse, causing sands to shift and the coastline to erode at a rate of 5 feet per year , rapidly changing the landscape around this monument, reported Atlas Obscura.

2. Kiipsaare Lighthouse, Estonia

Located on the tip of Harilaid Peninsula in Saaremaa, Estonia, the Kiipsaare Lighthouse was built in 1933 to warn mariners on the Baltic Sea about the dangers in the vicinity of the peninsula. It was originally built 328 feet from the coast but due to changes in the shoreline, it is now located in sea waters, according to VisitEstonia.com. Storms and waves, and a lack of supporting ground, have also caused the lighthouse to lean, earning it the nickname "Pisa Tower of Saaremaa." Later, the waves started causing the erosion of the soil from the other side, reversing the tower's tilt.

From 1992 to 2009, the lighthouse functioned as a daymark, but it is no longer used as a navigational aid , according to the Estonian Lighthouse Society.

3. Lighthouse in Klein Curacao, Curacao

The barren and uninhabited island of Klein Curacao (Little Curacao) in the Dutch Caribbean island of Curacao is a popular destination for divers and snorkelers, but it's also home to an unlikely attraction, a crumbling, 66ft-tall lighthouse, which has become the island's landmark.

Built in 1879 as a replacement to the island's original lighthouse, which was destroyed by a hurricane, the abandoned lighthouse was rebuilt again in 1913, but now stands alone in disrepair the center of the island. The wooden stairs to the top of the lighthouse are still intact, as are the two keeper’s houses flanking it. The lighthouse was abandoned decades ago but the light itself was reactivated in 2008 with a solar-power LED beacon , according to KleinCuracao.info.

4. Lighthouse of Ponta dos Capelinhos, Azores

Located along the coastal peninsula of Ponta dos Capelinhos and Costa Nau, on the island of Faial in the Porutguese archipelago of the Azores, the lighthouse, which was built in 1894, was abandoned in 1957 due to the year-long eruption of the Capelinhos volcano, which also destroyed surrounding buildings. The first floor of the building remains buried in ash. In 2008, a visitor center was opened in a new building near the abandoned lighthouse. The center is designed to preserve the existing landscape of the area affected by the eruption.

5. Southerness Lighthouse, Scotland

Southerness Lighthouse, located in the village of Southerness in Dumfries and Galloway in South West Scotland, is the second oldest lighthouse in Scotland. The lighthouse, which stands around 55ft tall and has a distinct square shape, was built in 1749 to serve as a beacon for shipping in the Solway Firth but didn't have a light until1800. It served the coastlined for over 100 years until it was decommissioned in 1936. It now serves as a historic landmark.

6. Talacre Point of Ayr Lighthouse, Wales

Located at Talacre Beach in Wales, the Point of Ayr Lighthouse was originally built in 1776 to help guide ships away from the nearby sandbanks and provide a bearing for the great port of Liverpool to the northeast. The lighthouse is around 60ft tall and originally featured two lights —one was directed at shipping out to sea while the second beam illuminated the mouth of the River Dee, according to BritainExplorer.com. It was one of the earliest "lantern" lighthouses in Wales, according to the Royal Commission on the Ancient and Historical Monuments of Wales (RCAHMW).

The lighthouse was decommissioned between 1883 and 1844, but today, it has become a popular landmark with visitors to the dunes and nearby holiday park, according to BBC News, which also reported in 2011 that the lighthouse was up for sale. Many believe, however, that the lighthouse is haunted. People who live nearby claim to have seen "ghostly lights" and a "distinct figure prowling the light room and balcony dressed in old-fashioned lighthouse keeper clothes," according to BritainExplorer.com.

7. Tillamook Rock Light, Oregon

Located a mile off the Oregon Coast, Tillamook Rock Light was officially lit on January 21, 1881, and at the time, it was the most expensive West Coast lighthouse ever built. Set 20 miles south of the mouth of the Columbia River and constantly slammed by furious waves, the lighthouse was nicknamed "Terrible Tillie," according to the New York Times. Deemed to dangerous (a storm in 1934 sent basalt fragments weighing 100 pounds crashing through the tower glass, according to the StatemansJournal.com) and expensive to operate, it was decommissioned and replaced by a whistle buoy in 1957.

In 1980, the lighthouse was purchased by Eternity by the Sea Columbarium, who placed about 30 urns in the site, but a state board shut the company down, saying the owners have not kept accurate records of people placed there and that because urns sit on boards and concrete blocks, not in niches, the lighthouse did not even qualify as a columbarium, reported the New York Times.

8. Waugoshance Light, Michigan

Located in northern Michigan and built in 1850 to mark a dangerous shallow area of northern Lake Michigan in the approach to the Straits of Mackinac, the lighthouse at Waugoshance was arguably the first light built in the Great Lakes that was totally surrounded by water.

In its glory the Waugoshance Lighthouse sported red and white horizontal strips on a steel encased tower and stone walls that are five and one half feet thick , according to the Waugoshance Lighthouse Preservation Society. The tower was crowned with a large "birdcage" lantern, one of only three lighthouses to be equipped with this style of lantern room in all of the Great Lakes. Waugoshance Lighthouse served until 1912, when it was replaced by White Shoals Lighthouse.

9. Malmok Lighthouse, Bonaire

Located at the northern tip of Bonaire, an island municipality of the Netherlands in the southern Caribbean, the Malmok meteorological station/lighthouse was built in 1906 but was never lit and deemed too close to the sea. It was replaced by another lighthouse, Seru Bentana, located nearby. The Malmok lighthouse is now in ruins. It was reportedly struck by lightning during a storm in 1954, causing a fire that burned the lighthouse to the ground.

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