Two excellent places to see the limestone underbelly of the Florida Keys are Windley Key Fossil Reef Geological State Park and the Marvin D. Adams Waterway. Both are in the Upper Keys; one is easier to reach than the other.
At Windley Key, exposed limestone walls standing eight feet tall were left exposed by quarry operations that went on for decades – drive in, park the car and walk right up. As advertised, they reveal the fossilized remains of an ancient coral reef.
To see different exposed limestone walls that tell the same story from a different point of view, the waterway requires a little extra effort: a boat ride through the middle of Key Largo.
The waterway was not naturally formed; technically, it split the largest island in the Florida Keys into two pieces. Key Largo’s size was one reason a plan formed to carve it through the middle of the island.
The waterway connects Largo Sound, on the ocean side of the island to Blackwater Sound on the bay side. Its creation took time and vision. Marvin Adams used both to accomplish the feat.
Marvin Dow Adams was born in Lamar, Missouri, on Aug. 11, 1898. As a young man, he married Leila Jane Sweeting; they had two children. About 1925, they moved to Miami, where Frank Egbert Sweeting, his father-in-law, liked to vacation and fish. He also made several real estate investments.
Sweeting lived in Bloomington, Indiana, and worked at the Beich Company. The firmmade confections, including Katydid Peanut Clusters and, much later, Laffy Taffy, launched in 1971 and introduced as a tie-in to the movie “Willy Wonka and the Chocolate Factory.” Sweeting introduced the family to Key Largo. In those days, the only way to reach the island was by boat or railroad.
He bought property on the island in 1923 that included a fisherman’s cottage built in 1917, and he retired from the candy business in 1925 to spend more time fishing and developing his South Florida properties.
One tract he purchased included the fishing cottage overlooking Largo Sound near what is now MM 103. He subdivided the tract into about 300 lots and named it Anglers Park; F. E. Sweeting developed, owned and operated the project. The real estate office was in Miami; Adams was the sales manager. An advertisement printed in the Aug. 29, 1926, Miami Herald declared: “Key Largo ‘Isle of Dreams’ is destined to become one of the most noteworthy and exclusive residential communities in the Southland. The most charming and desirable spot on Key Largo is Anglers Park.”
Adams was more than a sales manager. He had a law degree from the University of Chicago. In 1926, he served as president of the Miami Agency insurance group. In 1933, he was a director at the First Federal Savings and Loan Association of Miami. He served as chairman of the Turnpike Authority in 1953-1954. He was also a direct descendant of John Quincy Adams, the sixth president of the United States.
After the death of his father-in-law in 1950, Adams bought land on Key Largo, about 50 acres that included the Sweeting property and the island’s narrowest stretch. At about one-half mile wide, that stretch of the island is now recognized as the Marvin D. Adams Waterway.
The plan was to create a shortcut. For Key Largo boaters traveling from the oceanside to the bayside, there were two choices: Jewfish Creek and Tavernier Creek. With nearly 20 miles between them, a third option was welcomed. The United States Coast Guard liked the idea, too.
Carving an island the size of Key Largo into two pieces was no small task. The project began in the late 1950s and required 18 months of excavating. Mathew “Barney” Waldin did the digging. Much of the work was done with dynamite dropped into holes drilled 32 feet deep, which blew the coral rock into pieces. The sides were cut with a machine designed and created by Waldin with the help of an investor named Vining. They built something that could, according to a quote from the Miami Herald on May 25, 1976, “cut through coral rock like cheese.”
Waldin did not charge Adams for his service; instead, he was given all the coral rock he dug up, which he then sold. There was a lot of coral rock. When he finished carving out the waterway, he left the ends standing so no water could flow through it. Alonzo Cothron took out the ends, opened it to the sounds, and let the water pass through. The average depth of the cut is about 25 feet. The limestone walls, Key Largo’s underbelly, rise about 15 feet from the waterline.
It was called the Key Largo Waterway when it opened to boat traffic on Feb. 26, 1961, and not formally dedicated for years. Mayor Harry Harris wrote a resolution to rename it to honor the man responsible for its creation. When it was finally dedicated on Sunday, May 23, 1976, the name was changed to the Marvin D. Adams Waterway.
Though Adams died of a heart attack at his home in Coral Gables on Dec. 29, 1977, the family still has roots navigating the Key Largo limestone. Of course, there is the waterway, but also the family home overlooking Largo Sound, where the fisherman’s cottage still stands.
The property hasn’t been forgotten and will host a murder mystery dinner fundraiser for an excellent cause: the Good Health Clinic. They have offices in Tavernier and Marathon. Both work to provide health care to the financially struggling, uninsured residents of the Keys. Donations are a prime source of their funding. One annual fundraiser is the Kahuna Challenge. It invites people to donate to keep their doors open. Jaclyn Kelly, broker/owner at Better Homes and Gardens Real Estate Destinations and Star Properties Destinations, is working to earn the title of 2026 Big Kahuna. Kelly’s big fundraising event is a murder mystery dinner created with the help of her right and left hands, Samantha Arce and Katie Brennan.
To support the Good Health Clinic and learn more about the Kahuna Challenge and how you can participate, visit thegoodhealthclinic.org.
