Of all the animals that inhabit Wyoming's rivers and lakes, few delight observers as much as the river otter. Sleek, energetic, and seemingly always at play, the otter injects a note of pure exuberance into the state's waterways.

Superbly built for aquatic life, the otter has a streamlined body, webbed feet, and dense waterproof fur that let it hunt with remarkable agility underwater. It preys mainly on fish, along with crayfish, frogs, and other aquatic creatures, twisting and darting through the water with astonishing speed and grace.

What captivates people most, however, is the otter's apparent playfulness. They slide down muddy or snowy banks, wrestle with one another, and frolic in a way that looks unmistakably like fun, behavior that serves to build social bonds and hone hunting skills. A family of otters at play can hold a watcher spellbound.

The otter's presence is also a good sign for the health of a waterway, as the animals require clean water and abundant prey to thrive. Their recovery in some areas reflects improving conditions in the state's rivers. For the fortunate observer who spots a sleek head cutting through the water or a family sliding down a bank, the river otter offers one of the most joyful wildlife encounters Wyoming has to give.