Based on the adult manga by Sawaru Erect.

What animals can't swim?

Camels, giraffes, porcupines, rhinos can't swim. Camels and giraffes are not exposed to such deep water during their lifetime due to their height and hence adaptations were mainly focused on rest. And it's interesting to note that HIPPOS CANT SWIM EITHER.
Although they spend much of their time in the water, hippopotamuses are one of the few animals unable to swim.
Their inability to swim is partially due to their density.
Instead, they walk or gallop along the bottom of the river.