Please note: The Thacher Island North tower will be closed to climbing in 2020 due to repair work.
The South tower will be available to climb, although entrance to the outdoor parapet will be restricted.
Climbing Thacher Island Twin Towers
The Thacher Island towers are identical and were completed in 1861. They are each 124 feet high, with 156 steps to the top, and stand about 164 feet above the waterline. Each tower is 22 feet in diameter at the base and narrows to 13 feet at the lantern room. They are constructed of solid granite on the outside with a two-foot thick inner wall of brick. Each block of granite weighs over 10 tons.
From the tower one is able to see the skyline of Boston to the south, and the mountains of Maine to the northwest. Looking down to the southeast about a half mile offshore you may see an iron pole jutting out from the water. This marks an area called the “Londoner” so named because of the reef just below the surface which has claimed hundreds of vessels, most bound to Boston from London in the early 1700s. This reef was one of the reasons the original twin towers were built by the British of Massachusetts Bay Colony in 1771. The other reason was to be able to differentiate Cape Ann Light Station from Boston Light to the south and Portsmouth Light to the north.