The buried seafloor seismometer at H2O consists of two sensors: a Guralp CMG-3T three-component broadband seismometer and a Geospace HS-1 three-component 4.5-Hz geophone. For each channel, two levels of analog gain are applied (high gain and low gain) prior to digitizing at 160 samples per second (sps) using 16-bit digitizers. The data are available from Incorporated Research Institutions for Seismology Data Management Center (IRIS-DMC) in standard for exchange of earthquake data (SEED) format at a variety of sampling rates. All of the results displayed here are based on the 12 160-sps data sets. Table T1 gives a summary of the channel identifiers. It is important to note that the gain was changed during the experiment for the vertical component of the Guralp sensor on JD360/2001 at 14:40:15 hr UTC. The data and transfer functions were updated at the IRIS-DMC in November 2002, the high-gain data displayed here were downloaded in January 2003, and the low-gain data displayed here were downloaded in February 2004.