The GFDL Modular Ocean Model was designed with one purpose in mind: to maximize scientific productivity within the research environment at GFDL. As indicated in the introduction, the computational environment at GFDL has undergone change with each new computer procurement. To keep pace, efforts have focused on developing one model capable of taking advantage of scalar, vector and multiple processors within this increasingly varied computational environment. At the same time, consideration has been given to organizing the model to allow a large number of options, diagnostics, and physics parameterizations to co-exist in a way that is understandable, extendable, and easily accessible to scientists. In one sense, the design was strongly influenced by having CRAY vector platforms as the computational workhorses at GFDL since 1990. Although changes have been introduced to take advantage of scalability on multiple processors, the focus has remained on factors that influence overall scientific productivity and the design continues to be motivated by a search for a better way to do science from the trenches of scientific programming. As such, the scientific generality and flexibility within MOM make it well suited for use by the general oceanographic community10.1. The following factors are considered to be important in maximizing overall scientific productivity.