A spiral, cast-iron stairway provided access from the dwelling to a circular lantern room, which was surrounded by a cement gallery and a cast-iron balustrade. A sixth-order Fresnel lens, manufactured in France by Barbier & Benard, was mounted atop a cast-iron pedestal in the lantern room at a height of sixty-eight feet above the surrounding water. The light’s early signature was fixed-red, visible from a distance of eight miles.
When the United States took control of Puerto Rico in 1898, at the end of the Spanish-American War, the following information was published on Vieques Island, the largest of the Passage Islands lying between Puerto Rico and the Virgin Islands:
Crab Island, called also Vieques Island, six miles to the eastward of Puerto Rico, is the largest and most important of the Passage group, being 17 miles long by five broad. A ridge of small hills runs nearly its whole length along the middle of the island and rises to a moderate height at the southwest extremity of the island. …
On the northern shore of Crab Island is Port Mula, at the mouth of a little stream. It contains about 1,000 inhabitants and is the residence of the governor, who is nominated by the captain general of Puerto Rico.
There is a lighthouse erected at Mula Point, from which a fixed red light is exhibited. There is comparatively no trade except fruits and fish in this archipelago, but undoubtedly these islands are capable of development and will pay a fair revenue after they have become a portion of the United States. Their natural beauty is unsurpassed, and over them the trade wind is continually blowing, giving them a warm delightful climate.
Just a head keeper was assigned to Punta Mulas Lighthouse, as an assistant was not required to help with the station’s fixed, sixth-order lens. Cayetano Valie was in charge of the station from 1930 to 1932, and in 1931, he was commended for rescuing two men whose lives were imperiled off the north coast of Vieques near the lighthouse.
Punta Mulas Lighthouse was remodeled in the early 1940s. At that time, the brick roof was replaced by one built of reinforced concrete. The storage/oil room was converted into a pantry and dining room, the vestibule became the living room, the office became the storeroom, and the former living room was made into an office. More changes were made in 1944, when the new pantry/dining room was made into a power plant and battery room, the storeroom was converted into a modern bathroom, and a portion of the office was remodeled to serve as a storeroom.
The lighthouse was automated and left unattended starting in 1949. However, a caretaker started living in the dwelling in the 1960s, which prevented the structure from falling into disrepair.
Punta Mulas Lighthouse was restored and opened to the public as a museum on October 12, 1992 in celebration of the 500th anniversary of Christopher Columbus’ first voyage to America. By 2005, however, the lighthouse had suffered water damage and was closed to the public. The color of the lighthouse was changed in 2014 from gold and white to gray and white.