Likely excavation conditions during the proposed deepening of the boat channel at St. Kilda were investigated by drilling and seismic refraction surveys. Results showed 2 to 3 m of St. Kilda Formation (loose shelly sand) overlying up to 0.2 m of Glanville Formation (rubbly calcreted shelly bed) with over 10 m of Hindmarsh Clay (stiff to very hard clay) beneath. A backhoe should be capable of excavating all materials encountered in the channel. The Hindmarsh Clay is considered to have caused refusal of a dragline bucket during previous excavation attempts.