This document specifies requirements and provides recommendations and guidelines for marine soil investigations regarding: a) objectives, planning and execution of marine soil investigations; b) deployment of investigation equipment; c) drilling and logging; d) in situ testing; e) sampling; f) laboratory testing; g) reporting. Although this document focuses on investigations of soil, it also provides guidance, with less detail, for investigations of chalk, calcareous soils, cemented soils and weak rock. Foundation design is not covered by this document. NOTE 1 ISO19901?4 and the respective design standards covering foundation design for the specific types of offshore structures to meet the requirements of application specific standards are given on the ISO website. The results from marine geophysical investigations are, when available and where appropriate, used for planning, optimization and interpretation of marine soil investigations. This document neither covers the planning, execution and interpretation of marine geophysical investigations nor the planning and scope of geohazard assessment studies, only the corresponding marine soil investigations aspects thereof. NOTE 2 ISO 19901-10 covers the planning, execution and interpretation of marine geophysical investigations. This document specifies requirements and provides guidance for obtaining measured values and derived values. This document excludes requirements for determination of design values and representative values. Limited guidance is provided in 11.3 related to data interpretation. This document is intended for clients, soil investigation contractors, designers, installation contractors, geotechnical laboratories and public and regulatory authorities concerned with marine soil investigations for any type of offshore structures, or geohazard assessment studies.