A caiman opens its mouth to cool off while sunbathing along the Frio River's shore on March 9, 2013.

Caño Negro Wildlife Refuge

Tags canals, rainforests, wetlands, wildlife refuges, rivers

Caimans bathe with wide-open mouths on the banks of the Frío River in the Cano Negro Wildlife Refuge. Above them in the trees, the second loudest animal in the world, the howler monkey bellows its wild, vicious roar. If you're lucky, you might even catch a glimpse of a rare albino monkey that lives with a troupe of howlers in the trees along the river.