“As two spent swimmers, that do cling together”

With this phrase, Shakespeare makes a relation between the battle of Macdonwald and King Duncan’s men, to a pair of struggling swimmers. The intent behind this metaphor is to imprint an image of the battle into the minds of the audience. The word “cling” makes both characters sound desperate and helpless, which is slightly ironic as they are in conflict with eachother.

Modern day English : “Just like two physically drained swimmers, who are hanging onto eachother for dear life.”