Carbonate sediments are prevalent in many major offshore oil and gas basins, as well as a growing number of regions assigned to offshore wind development. Identified as difficult from an engineering perspective, the failure to properly characterize and design for these sediments has adversely influenced several projects. This paper provides a brief geological perspective, and identifies broad trends and characteristics to be considered when defining the engineering properties of such materials. An overview of the challenges faced when founding offshore structures in such sediments is provided, drawing on experience gained over the last 30 years, and with an emphasis on current and emerging issues.