A lion swimming in the ocean? If you placed it near a river, or some sort of freshwater source, that'd make sense. But you find yourself in the ocean, a 20ft wave — I'm assuming it's off the coast of South Africa — coming up against a full grown 800lb tuna with his 20-30 friends?
They bypassed the terrestrial food chain to tap into a vast, unexploited energy source: Ocean
These desert lions depend on marine prey for >85% of their diet. They hunt fur seals & coastal birds such as cormorants & flamingos.
They have phenotypic adaptations to survive in coastal deserts: leaner bodies, longer legs, & highly efficient metabolisms, allowing them to go days without fresh water.
The local coastal lion population in Namibia went extinct in 1980s, & it was once thought that the knowledge of hunting marine prey had gone extinct with them.
However, in the early 2000s, a few lions recolonised Skeleton Coast National Park. Initially, they were wholly dependent on terrestrial prey like zebra & oryx, much like typical savannah lions.
The severe drought of 2015 made terrestrial prey scarce, pushing a few orphaned lionesses to shift back to marine prey.
Since lions are highly social creatures, this knowledge of hunting marine prey has been continuously passed down to incoming generations.
This is the only wild lion population that mainly lives & feeds in marine environments.