The first luxury single-family residences at SeaGlass Cove in the Florida Keys are set to be delivered in March 2024. SeaGlass Cove is a new, luxurious island enclave consisting of just 14 single-family homes in Marathon, Fla., in the heart of the Florida Keys. Located at 59720 Overseas Highway in Grassy Key, the project is being developed by Constellation Group and Ironwood Venture Group.