What metric is your swim workout worth vs. other exercise options?

NewScientist published an article yesterday summarizing the science of fitness.  One of the topics covered just what counts as exercise.  They gave the example of golf  and the age old question of whether it truly is exercise.  Quick answer, yes - if you walk.  Less so, if you ride a "buggy".  How do they assess this? The article cites a compendium of data pulled together by university researchers (a Stanford researcher conceptualized the concept while the University of South Carolina developed the PDF cited below ) that details each type of exercise and its MET or metabolic equivalent, and yes, swimming is included.  Not only that, but each type of swimming activity, ranging from general leisure (not lap) swimming, to easy lap swimming, to vigorous lap swimming is there.  The compendium even breaks it down into type of stroke - breast, freestyle, and butterfly.  You can check out the compendium yourself, at this link.