An Etymological Dictionary of the German Language/Annotated/schwimmen
schwimmen, verb, ‘to swim,’ from the equivalent Middle High German swimmen, Old High German swimman; corresponding to the equivalent Old Saxon swimman, Dutch zwemmen, Anglo-Saxon swimman, English to swim; Old Icelandic symja points to Gothic *sumjan (preterite swam). Akin also to Gothic swamms, ‘sponge,’ swumfsl, masculine, ‘pond.’ The Teutonic root swëm, sū̆m, appears also in Sund; compare also Old Icelandic svamla, Middle High German swamen, ‘to swim.’ In the non-Teutonic languages the root swem, sū̆mm, ‘to swim,’ has not yet been found.