The in situ measurement of seafloor physical properties such as pore pressure, shear strength or compressibility poses a challenge to engineers, in particular in the marine realm. We present the design and first use of a marine, deep-water free-fall instrument for cone penetration testing (CPT). The probe can be operated in up to 4000 in water depth to measure cone resistance, sleeve friction, deceleration, temperature and tilt as well as pore pressure in u(1) and u(3) position. In this paper we discuss the advantages and disadvantages of the current prototype design, and dwell on the differences between quasi-static versus dynamic cone penetration testing.
