SEACOOS White Paper for the Maritime Safety and Offshore Operations Theme (First Draft, 4 JUL 05; Revised Drafts, 11 & 14 JUL 05, based, in part, on comments received from Bob Weisberg, Madilyn Fletcher, Harvey Seim, Lundie Spence, and Cj Beegle-Krause & Glen Watabayashi, NOAA/HAZMAT; RevisedPresent Draft, 30 OCT 05, based, in part, on discussions at the SEACOOS Summer 05 WS; Present Draft, 8 NOV 05, based on additional comments received from Cj Beegle-Krause;  provided by Chris Mooers) Introduction. The scope of the Maritime Safety and Offshore Operations (MS&OO) Theme includes provision of the environmental information needed for Search-and- Rescue (SAR) operations; response to deleterious substance spills (e.g., oil, toxic chemicals, disaster management , and sewage); mitigation of impacts due to harmful algal blooms (HABs); safe and efficient navigation; engineering design studies for submarine pipe lines, outfalls, and offshore structures; support of forensic activities engaged in reconstruction of marine event scenarios, etc. {NOTE: presently, MS&OO does not include activities associated with storm surge, rip currents, king waves, beach erosion, etc. in anticipation of the Waves Theme possibly morphing into a Coastal Hazards Theme.} {NOTE: presently, MS&OO is only considering waterborne transport/dispersion. However, as our capability in coastal marine meteorology expands, we will almost inevitably also address the important topic of airborne transport/dispersion in at least the coastal marine boundary layer.} The environmental information requirements for MS&OO include the basic physical variables (i.e., surface winds, sea state, air temperature, ambient currents, horizontal turbulent dispersion, vertical turbulent mixing, temperature, and salinity). It is essential that this information be available in real-time (within ca.1 hr delay). The information may be based upon expert analysis, climatology, synoptic (in situ and satellite and other remote sensing) observations, and/or numerical predictions. Typical horizontal domain scales range from 10 to 100 km, and time domain scales range from a day to a week or more. The desired horizontal resolution is 1 km or less on the continental shelf and 100 m or less in the estuaries, and the desired time resolution is 1 hr or less. The highest priority has typically been placed on surface fields; however, subsurface fields are often of importance, too, when the material of concern sinks or is mixed into the water column. For many, the environmental information is most usefully presented in a map format, while vertical and horizontal profiles and time series data are valued by others. To summarize the synoptic situation through a synthesis of all available information, “ocean weather maps” with the position of ocean fronts, eddies, and meandering jets, and particle trajectories and dispersion clouds displayed are particularly effective in conveying the essence of the environmental situation to on-the scene-commanders who are very busy dealing with the full range of operational response issues.  Such synoptic ocean maps, together with conventional mesoscale marine weather charts, need to be updated several times per day. Electronic maps should be georeferenced. Downloadable fields would be 1