Earthquakes are constantly shaking the deep seafloor. While most of the smaller ones go unnoticed, the largest can produce devastating tsunamis, as recently seen in Japan and Sumatra. Recording these deep sea earthquakes presents a significant technical challenge. A team of Lamont scientists and engineers build and deploy rugged instruments designed to survive the extreme seafloor environment and collect vital earthquake data. Results of this work are advancing our understanding of earthquake processes and may one day lead to improved forecasting for large tsunami-generating earthquakes.