SUMMARYThe expansion of offshore renewable energy infrastructure and the need for trans-continental shelf power transmission require the use of submarine High Voltage (HV) cables. These cables have maximum operating surface temperatures of up to 70 o C and are typically buried 1-2 m beneath the seabed, within the wide range of substrates found on the continental shelf.However, the heat flow pattern and potential effects on the sedimentary environments around such anomalously high heat sources in the near surface sediments are poorly understood. We present temperature measurements from a 2D laboratory experiment representing a buried submarine HV cable, and identify the thermal regimes generated within typical unconsolidated shelf sediments-coarse silt, fine sand and very coarse sand. We used a large (2 x 2.5 m) tank filled with water-saturated spherical glass beads (ballotini) and instrumented with a buried heat source and 120 thermocouples, to measure the time-dependent 2D temperature distributions.The observed and corresponding Finite Element Method (FEM) simulations of the steady state heat flow regimes, and normalised radial temperature distributions were assessed. Our results show that the heat transfer and thus temperature fields generated from submarine HV cables operating at the grain and sub-grain scale; biological activity at both micro-faunal and macrofaunal levels; and indeed the operational performance of the cables themselves, as convective heat transport would increase cable current ratings, something neglected in existing standards.