Understanding intrasalt structure and composition helps to: (i) determine the kinematics of the growth of salt diapirs; (ii) predict drilling hazards when exploring for hydrocarbons or minerals; and (iii) build better subsurface velocity models for seismic reflection imaging. However, our understanding of the internal structure and composition is poor because: (i) well-exposed, natural salt diapirs are rare because halite, a key component of many salt structures, is highly soluble and dissolves, whereas anhydrite, upon contact with water, converts to gypsum, leaving a karstic soil or crust that masks the diapir’s internal structure; (ii) the internal structure of exposed diapirs can be strongly deformed by gravity spreading of salt extruding at the Earth’s surface; (iii) even where diapirs are well exposed at the Earth’s surface, exposures are largely two-dimensional; and (iv) thick salt is typically acoustically transparent on seismic reflection data, and internal stratigraphic markers that record strain are typically poorly imaged. In this session we welcome contributions from geologists, geophysicists, and numerical and physical modellers interested in the style and implications of intrasalt structure and composition.