New London - The approach was straight out of a spy caper.

Capt. Katie Beal steered her 23-foot Seacraft onto a small beach where the occupants jumped out and scrambled up rocks, a stealthy approach to the New London Harbor Light.

What lay ahead, though, wasn't a thuggish security guard but tour guide Alexander MacDonald.

And the promise of a clear view miles out into the horizon.

MacDonald, who works with the Custom House Maritime Museum, led three tours Saturday up the 89-foot lighthouse as past of the museum's "Sentinels on the Sound" event.

The three-day event, which runs through Sunday, is to celebrate New London's lighthouse heritage, said organizer Susan Tamulevich, director of the Custom House Maritime Museum/New London Maritime Society.

The museum recently acquired the lighthouse from the Coast Guard, MacDonald said, meaning those touring Harbor Light were some of the first members of the public to see the inside of one of the oldest lighthouses in North America.

"The original was built in 1760, but a crack in the foundation led to this lighthouse being built in 1801," MacDonald said. "Two of the three older than Harbor Light are Sandy Hook in New Jersey and the lighthouse in Boston Harbor."

The six visitors used a rope railing to walk up 120 steps - counted by 11-year-old Tatiana O'Hanlon - to the top.

From there, on a clear night, MacDonald said, you can see the largest number of lighthouses of any spot in the world - sometimes up to nine stretching from East Lyme to Stonington and out to Fishers Island.

On this clear Saturday, Ledge Light, Avery Point and Race Rock lighthouses were visible. Light glinted off the small whitecaps far below, and boats' sails fluttered in the wind.

"Harbor Light is still used as a navigational aid to this day," MacDonald said. "If you see red light, you're too close to the rocks."

The light itself has undergone transformations as well, MacDonald said.

Parabolic mirrors and oil-lit candles were used before it switched to a powerful Fresnel lens and eventually automated electricity in 1912, MacDonald said.

A lighthouse keeper was no longer needed, MacDonald said. The formerly attached keeper's home was sold to a private owner.

For some, it was a vastly different view of the neighborhood.

Holly Sena and Jeff Goldschmidt, and their 5-year-old son Max, live around the corner on Parkway South and were excited to get a look from the tallest building in the area.

Their neighbor, Marvin Berger, 85, said he's lived on Parkway South for 40-some years and wanted to see the structure, which had been off-limits to the public until now. His daughter, Mary-Sarah O'Hanlon, traveled from Ashby, Mass., with her daughter Tatiana to walk the winding staircase.

Capt. Beal, who dutifully waited with her boat, took the group around the mouth of the Thames River on the way back to the Custom House pier. Beal circled Ledge Light and approached the Avery Point Lighthouse before depositing her crew and picking up the next group of adventurers at the dock.

All the tours were sold out, Tamulevich said, prompting the museum to consider offering lighthouse boat tours during the first weekend of each of the summer months.

The feedback, she said, was overwhelmingly positive.

s.goldstein@theday.com