As offshore wind energy development progresses into deeper waters, the challenges associated with geotechnical investigations have become increasingly pronounced. This is primarily driven by the expansion of project scope, the stringency of time constraints, and the growing demand for high-precision, reliable site data. This paper uses the world's largest single-unit offshore floating wind turbine, OCEAN X, as a case study to outline the geotechnical investigations and soil parameter testing required for the foundation design. This study examines the methodologies for obtaining marine sediments parameters and addresses critical issues related to site investigations for deep-sea floating wind turbines. Firstly, a recommended protocol was proposed to streamline geotechnical investigations by eliminating redundant testing and data collection to enhancing overall efficiency and adaptability to the growing scale of deep water wind farms. Additionally, the study emphasizes the necessity of high-precision sampling methods at critical locations to mitigate sampling disturbance and secure reliable, representative geotechnical data, especially for highly structured soils. Finally, the practical application of geotechnical parameters in cyclic foundation design is discussed, incorporating consistency verification between in-situ and laboratory-derived data to ensure parameter reliability, along with suggestions for adapting testing methods to better reflect marine sediment behaviour. Together, these insights offer practical basis and valuable guidance for optimizing geotechnical investigation procedures and contribute to the development of more durable and sustainable foundations for floating wind turbines subjected to marine cyclic loadings. • Focus on marine geotechnical investigation and soil testing for suction anchor foundation of floating wind turbines. • Proposing a recommended protocol for marine geotechnical investigations to improve overall efficiency. • Quantifies the impact of sample techniques on the accuracy of the geotechnical parameters. • Verifying the consistency between in-situ and laboratory test results through key parameters such as OCR and S u .
Liao et al. (Thu,) studied this question.