| SPORTS FISHING HALL OF FAME, INC.Location not reported, FL · Inactive | Location not reported, FL | Nonprofit | Apr 2, 1968 | Inactive |
| ATLANTIC RESEARCH TECHNOLOGY OF OCEONOGRAPHY, INC.Location not reported, FL · Inactive | Location not reported, FL | Nonprofit | Mar 25, 1969 | Inactive |
| GREATER MARATHON RESORT ASSOCIATION, INC.Location not reported, FL · Inactive | Location not reported, FL | Nonprofit | Dec 5, 1969 | Inactive |
| THE OPTIMIST CLUB OF MARATHON, FLORIDA, INC.Location not reported, FL · Inactive | Location not reported, FL | Nonprofit | Mar 23, 1970 | Inactive |
| MARATHON FLYING CLUB, INC.Location not reported, FL · Inactive | Location not reported, FL | Nonprofit | Dec 29, 1970 | Inactive |
| DUCK KEY PROPERTY OWNERS ASSOCIATION, INC.Duck Key, FL · Inactive | Duck Key, FL | Nonprofit | Apr 23, 1971 | Inactive |
| FLORIDA KEYS SPORTS FISHING ASSOCIATION, INC,Location not reported, FL · Inactive | Location not reported, FL | Nonprofit | Apr 23, 1971 | Inactive |
| MARATHON ANIMAL SHELTER, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jun 7, 1971 | Active |
| BONEFISH TOWERS CONDOMINIUM, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jun 7, 1971 | Active |
| SOMBRERO RIDGE CONDOMINIUM, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Nov 1, 1971 | Active |
| MANOR LANE ASSOCIATION, INCMarathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 26, 1972 | Inactive |
| TRADE WINDS WEST CONDOMINIUM INCMarathon, FL · Active | Marathon, FL | Nonprofit | Mar 20, 1973 | Active |
| GUIDANCE/CARE CENTER, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | May 28, 1973 | Active |
| THE LADY ALEXANDER ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Oct 25, 1973 | Active |
| ISLAND CLUB CONDOMINIUM, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Oct 25, 1973 | Active |
| DUCK KEY SAILFISH TOURNAMENT, INC.Location not reported, FL · Inactive | Location not reported, FL | Nonprofit | Nov 8, 1973 | Inactive |
| ROYAL PLUM CONDOMINIUM, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jan 7, 1974 | Active |
| THE LEMON COVE CONDOMINIUM, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Feb 18, 1974 | Active |
| HAWK S NEST CONDOMINIUM, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jun 26, 1974 | Inactive |
| BOOT KEY VIEW CONDOMINIUM, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 2, 1974 | Active |
| GREATER MARATHON SAWFISH TOURNAMENT, INC.Location not reported, FL · Inactive | Location not reported, FL | Nonprofit | Sep 27, 1974 | Inactive |
| CORAL CLUB CONDOMINIUM, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Oct 16, 1974 | Active |
| THE SCHOONER, A CONDOMINIUM, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Dec 17, 1974 | Active |
| THE SPANISH GALLEON, A CONDOMINIUM, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Dec 17, 1974 | Active |
| HARBOR CLUB SOUTH CONDOMINIUM, BUILDING NO. 1, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jan 22, 1975 | Active |
| MIDDLE KEYS CITIZENS ASSOCIATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Sep 3, 1975 | Inactive |
| HARBOUR HOUSE CONDOMINIUM, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Apr 15, 1975 | Active |
| CONCERNED CITIZENS FOR BETTER EDUCATION OF MARATHON HIGH SCHOOL, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Jul 25, 1975 | Inactive |
| MARATHON COUNTRY CLUB CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 25, 1975 | Active |
| MARATHON COUNTRY CLUB CONDOMINIUM WEST ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 25, 1975 | Active |
| MARATHON AND LOWER KEYS ASSOCIATION OF REALTORS, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Sep 16, 1975 | Active |
| THE FAITH BAPTIST TEMPLE OF MARATHON, FLA., INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Sep 17, 1975 | Inactive |
| ST. COLUMBA'S EPISCOPAL CHURCHMarathon, FL · Active | Marathon, FL | Nonprofit | Sep 19, 1975 | Active |
| MIDDLE KEYS CHAPTER #2324 OF AARP, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Oct 14, 1975 | Inactive |
| COMMERCIAL FISHERMEN ASSOCIATION OF MONROE COUNTY, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Nov 10, 1975 | Inactive |
| STIRRUP KEY HOMEOWNERS ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 18, 1976 | Active |
| OCEAN POINT VILLA CONDOMINIUM ASSOCIATION, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 18, 1976 | Active |
| MARATHON JAYCEES, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Aug 26, 1976 | Inactive |
| THE MARATHON COMMUNITY THEATRE INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Sep 8, 1976 | Active |
| INDIES ISLAND CONDOMINIUM, INC.Duck Key, FL · Active | Duck Key, FL | Nonprofit | Sep 9, 1976 | Active |
| HARBOUR CAY CLUB, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Nov 2, 1976 | Active |
| FLORIDA KEYS C.B. ORGANIZATION, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Nov 16, 1976 | Inactive |
| MARATHON DOLPHIN SCRAMBLE, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Apr 19, 1977 | Inactive |
| UPSTAIRS GALLERY, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | May 20, 1977 | Inactive |
| CRIME COMMISSION OF MONROE COUNTY, INC.Marathon Shores, FL · Inactive | Marathon Shores, FL | Nonprofit | Aug 25, 1977 | Inactive |
| DISABLED AMERICAN VETERANS CHAPTER 122 OF MARATHON, FLORIDA, INC.Marathon, FL · Inactive | Marathon, FL | Nonprofit | Nov 1, 1977 | Inactive |
| MARATHON YOUTH CLUB, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Mar 28, 1978 | Active |
| MARATHON J-KEYS, INC.Location not reported, FL · Inactive | Location not reported, FL | Nonprofit | Jun 29, 1978 | Inactive |
| MARATHON GARDEN CLUB, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Jul 14, 1978 | Active |
| FLORIDA KEYS LAND & SEA TRUST, INC.Marathon, FL · Active | Marathon, FL | Nonprofit | Aug 17, 1978 | Active |