"The goal of the Simple Ocean Data Assimilation (SODA) project is to reconstruct the historical physical (and eventually biogeochemical) history of the ocean back (eventually) to the beginning of the 20th century. As its name implies, SODA uses a simple architecture based on community standard codes with resolution chosen to match available data and the scales of motion that are resolvable. Agreement with direct measurements (to within estimates of the observational error) as well as unbiased statistics are expected. While SODA remains a university-based research project, we want to be helpful to users by providing a reliable, well-documented, source of seasonal-to-decadal scale ocean/sea ice reanalysis to complement the atmospheric reanalyses available elsewhere."