Lions are not solitary creatures. They stick to their pride. But as cubs, they can be curious little twats who go off roaming into areas they're not supposed to venture into. This is probably what happened to this cub, who somehow ended up on the wrong side of the torrential Ntiakitiak river, somewhere in the Kenyan wilderness.
Thankfully, badass mommy dearest happened to be nearby to get the cub back to safety. Because mothers will always be mothers.
Incidentally, Greek photographer, Kyriakos Kaziras, happened to be in the area. He clicked these amazing pictures of the lioness' rescue mission as she carried her cub across the river.