Why are crab-eating macaques able to access aquatic food sources that many other primates cannot exploit?

Answer

They are known to be excellent swimmers

A crucial element allowing them access to aquatic fare like crabs and oysters is their profound comfort in water; they readily enter the water, often diving beneath the surface to forage.

Why are crab-eating macaques able to access aquatic food sources that many other primates cannot exploit?
dietanimalCrabPrimateMacaque