For more than 35 years, interstitial water (IW) samples have been collected from sediment recovered during marine scientific coring expeditions. Pioneering work of DSDP and ODP quickly demonstrated that pore water chemistry differed from that of overlying seawater and from one location to another for myriad reasons (Sayles and Manheim, 1975). Extraction and analysis of IW samples has now becomeroutine on deep-sea drilling cruises; the ensuing pore water profiles are being used to understand a range of processes, such as subsurface fluid flow (e.g., Brown et al., 2001; Saffer and Screaton, 2003), mineral diagenesis (e.g., Rudnicki et al., 2001; Malone et al., 2002), microbial reactions (e.g., Böttcher and Khim, 2004; D’Hondt et al., 2004), gas hydrate dissociation (e.g., Egeberg and Dickens, 1999; Tréhu et al., 2004), and glacial to interglacial changes in the composition of bottom water (e.g., Paul et al., 2001; Adkins and McIntyre, 2002)