A bump is a feature of rowing at Oxford and Cambridge. Due to the narrowness of the of the River Thames at Oxford and the River Cam at Cambridge, when rowing eights are racing there is a staggered start since they cannot row abreast. Instead, eights must aim to catch up with and "bump" the eight in front. That is, they must touch or overlap with that eight. At this point, the cox of the eight that has been bumped should acknowledge the fact and both eights then retire from the race. Eights, especially the leading eight, may aim to "row over" (i.e., finish the race without being bumped). At the end of each day, eights are reordered for next day's racing and this continues for several days until the end of the regatta.