Meaning: The Pandavas crossed the battlefield like a river because Lord Krishna was their charioteer.
Reference: The present shloka describing the battle of Mahabharata has been taken from the poem काव्यमधुबिन्दवः. Here, the battle of Mahabharata is compared with a river. रण ख नदी (the battlefield itself is a river) this is a metaphor. Every river has (1) bank (2) water (3) water lily (4) narrow mouthed crocodile (alligator) (5) small boat (6) flow of water (7) crocodile and (8) whirls. The things, such as - Bhisma and Drona as bank, Jayadratha as water, Shakuni as waterlily, Shalyaraj as crocodile, Kripacharya as a small boat and Karna as flow of water. Ashwatthama and Vikarna are like a terrifying crocodile and Duryodhana acts as whirl.