I once heard the Thomas Point Shoal Lighthouse described as a Victorian rendition of a lunar landing module.

It’s an absurd image that stuck with me, not just for its succinct visual depiction of the structure — a white, six-sided, lapped-board cottage perched on spidery iron legs in the middle of the Chesapeake Bay — but also for the sense of vulnerability and isolation it evokes.A tour group gathers inside the Thomas Point lighthouse as docent Meg Govan tells tales of its history. (Kimbra Cutlip)

Indeed, there must be parallels between landing on the moon and spending weeks at a time encapsulated in a tiny shelter surrounded by a vast, inhospitable environment. That was the reality of life for a succession of lighthouse keepers who tended it for 111 years.

Today, the public can tour the lighthouse, in its original location just south of Maryland’s Bay Bridge, for a glimpse of that life. The light is operated by the Coast Guard and still serves as an active aid to navigation, but the house and structure were transferred to the City of Annapolis in 2004. They are being restored and preserved by the U.S. Lighthouse Society and its Chesapeake Chapter.

Run by the Lighthouse Society, the tours begin with a 30-minute boat ride from the Annapolis Maritime Museum and can accommodate up to 18 participants. As we motored out of Annapolis, four yellow-shirted docents chatted up passengers, eager to share their knowledge of the harbor, the Chesapeake and Thomas Point, an elbow of land at the mouth of the South River where a shallow shoal extends a mile and a quarter into the Bay.

The last manned lighthouse on the Bay, it hosted keepers until 1986 when the mechanism was fully automated. It is the only intact lighthouse of the “screwpile” design still in its original location. This design involved manually screwing long iron rods or pilings deep into the Bay’s bottom. Above the surface, the pilings at the lighthouse cant slightly inward and are braced with tie rods and steel I-beams. The resulting platform supports the 35-foot diameter hexagonal cottage and lends it the distinctly lunar-landing module appearance. It is arguably the most iconic light on the Chesapeake Bay.

“Thomas Point Shoal Light has six dormers,” docent Tom Cagle said as we sped toward our destination. “It’s the only one with six. Watch out for the model they sell in town. It only has two.”

A broad-faced retired Maryland Natural Resources police officer with an infectious smile, Cagle told us he called the manufacturing company with the hope of persuading it to rectify the error. Now that the error has been brought to my attention, I’ve noticed a lot of misidentified Thomas Point Lighthouses, including a photo in the National Archives.

The tour began on the open deck beneath the house. Meg Govan, a retired fifth-grade teacher and a docent since 2006, told us that, on the shore side of the lighthouse, the water is a mere 6– to 8-feet deep and becomes shallower all the way to shore. On the Bay side, it drops quickly to 35 feet. British ships, she said, ran aground in these waters twice during the War of 1812.

In the late 1800s, when the shoal was fertile ground for commercial oystermen, lighthouse keepers often recorded names of vessels working in their vicinity and helped to keep a watch for poachers. The lighthouse is now a popular spot for anglers, but the days of oystering the shoal are over.

Docent Chris Mulry explains the solar-powered light that operates in the lantern room and still serves as a navigational aid to ships on the Chesapeake Bay. (Kimbra Cutlip)So, too, are the days of screwpile lighthouses. Their downfall was caused by a once-common occurrence that is hard to envision today: ice. In recent decades, the navigable waters of the Bay have frozen enough to require Coast Guard icebreakers only a handful of times, but historically ice was a very real hazard. In the late 1800s, screwpile lighthouses at Love Point and Wolf Trap were destroyed by ice and one at Sharps Island was shorn from its foundation. Even the sturdier caisson light that replaced it was tilted by ice in 1977.

Thomas Point has withstood damaging ice since it was built in 1875, in part because of a steel wedge set on its own screw piles about 90 feet upstream, where it would split ice flowing down the Bay during the spring thaw. Riprap was also added over time, and the lighthouse stood its ground. But not without incident. In 1877, the lens was knocked from its base and broken. Keepers told the Baltimore Sun “the running ice shakes the light-house so much that the stoves have to be lashed down. At night the ice breaking against the piers sounds like the cracking of fire.”

In 1918 and 1940, heavy ice led to the evacuation of the cottage. In later years, the keepers endured hurricanes such as Agnes in 1972. Now, as the wakes of passing boaters slapped loudly but harmlessly against the iron rods and surrounding riprap, I reached up to touch the bottom of the lighthouse — the very floor that had shuddered and groaned violently beneath the keepers.

As Govan spoke, she was interrupted every seven minutes by the raspy, angry squawking of birds — or rather a recorded simulation of birds in distress. “It’s to keep the birds away,” she said. “If you see the picture of this lighthouse on the Weather Channel, the roof looks white because it’s covered in guano. It’s an old picture, from before the restoration.”

Fastidiousness was required of early lighthouse keepers, who were expected to wear their full woolen uniform at all times. Clearing bird poop from the roof would have been part of the daily routine, I suppose. Govan mentioned wanting to ask the Weather Channel to replace the photo with a new one now that the red metal roof is kept clean again.

After taking questions, she led us to the first floor of the house which we accessed by climbing a narrow ladder through a hatch in the wraparound porch. White gingerbread balusters form the porch railing.

The exterior boards of the cottage gleam with heavy layers of white paint, interrupted here and there by small pocks of black — wounds of rotted wood. Closer inspection revealed that they were actually quite prevalent on one side, but unnoticeable under patches of white duct tape. Before the Lighthouse Society took over, the building had fallen into disrepair. Restoration is clearly ongoing, but it appeared the duct tape was doing its job for now.

Inside, the restoration looks nearly complete with beautifully finished original hardwood floors, white tongue-in-groove walls and ceilings, period furniture and two wood stoves. The first floor is divided into four rooms, a sitting room and kitchen that approximate 1905 appearances, a head keeper’s bedroom that is still under renovation, and the “Coast Guard room” refurbished to its 1970s era radio room and office.

Throughout its life, the lighthouse was manned by three or four men working 12-hour shifts and rotating two or three weeks on duty with one week ashore. Rotating crewmen carried trash and mail, and a monthly tender delivered water, fuel and other provisions.

In the sitting room, Govan showed us the lighthouse version of a book mobile, a medicine cabinet-size bookshelf resting on the floor. Books were rotated between lighthouses up and down the Bay.The wraparound porch of the Thomas Point lighthouse offers scenic views in all directions.

In the kitchen, or galley, a list of annual allowances included early lighthouse staples such as coffee, tea, flour, baking powder, vinegar, beef, codfish, mutton, apples and 104 pounds of something called pilot bread. This is where I began to feel the constraints of a timed tourist expedition. Interesting information hung on the walls everywhere, but there was not enough time to read it.

Moving on to the radio room — a glaring example of the ill-conceived aesthetic of the 1970s, with its “government green” paneled walls and wheat-brown carpet squares — Govan discussed how life had changed for the keepers and then proudly showed us the careful restorations, which included a vintage television that a volunteer had carefully glued back together after vandals smashed it on the rocks below.

A spiral staircase leads to the second story of the lighthouse, which once housed the 1,000-pound fog bell keepers had to wind like a clock. The bell struck three times every 30 seconds when visibility was low. The volume must have been torture. Today, the National Oceanographic and Atmospheric Administration weather instruments operate in this space. (Anyone in the world can see conditions on the lighthouse at ndbc.noaa.gov/station_page.php?station=tplm2.)

A hatch in the ceiling and a ship’s ladder lead to the heart of the lighthouse, the lantern room. The low-wattage acrylic light is wired to a bank of four solar-charged marine batteries, but circular brass vents on each parapet remind me that it was once a living beacon with a flame that required tending. First oil, then gas vapor fueled the light, which was amplified by a 28-inch crystal Fresnel lens. It was electrified in 1933 and converted to solar in 1997.

Our hour on the lighthouse ended all too abruptly when the last of us had poked our head into the tower. I could have stayed all day trying to conjure up an obsolete way of life. I imagine time moved more slowly for the occupants of the lighthouse, but in the compression of its 150-year history, its keepers bore witness to significant changes in climate, technology and culture.

Today, their stories are being kept alive by a new breed of keeper — volunteers from the Lighthouse Society who lovingly scrape, paint, repair, and, yes, use duct tape, as well as docents like Govan and Cagle who lead tours and defend the image of the lighthouse against false replicas and outdated photos.

Tours of the Thomas Point lighthouse run on select Saturdays through early October. The cost is $80 per person and tickets can be purchased at uslhs.org/about/thomas-point-shoal-lighthouse/tours.  Note that guests must be at least 12 years old or 4-feet tall to safely navigate the ladders. Videos on safety and the history of the lighthouse are also available on the website. For information, call 415-362-7255 or email info@uslhs.org.