What are the unique challenges in offshore geotechnical engineering?

Offshore geotechnics challenges: (1) Site investigation - seabed CPT, box cores, seismic profiling from vessels with positioning challenges, (2) Foundation types - gravity bases, piles, suction caissons, spudcans for jack-ups, (3) Loading - cyclic wave/wind loads, strain rate effects on strength, (4) Soil conditions - often soft normally consolidated clays, carbonate soils (weak, compressible, cemented), (5) Installation - driving underwater, suction installation, (6) Scour protection, (7) Decommissioning considerations. Design codes include API RP 2A and ISO 19901 for offshore structures.