Griddled with roaring rivers and slashed through by tabletop mountains that wear bonnets of impenetrable Central American jungle, there's nothing of the relaxing, sun-kissed Caribbean in these parts of Belize. Nope; Cayo is for the adventurers, the trekkers, the ecotourists and the intrepid types. From the ramshackle hostels of Belmopan and San Ignacio, it's possible to join Cayo tour guides on dinghy trips down the Macal River that pierce through the misty forests in search of the fluttering tropical butterflies, red-hued parrots and even the elusive jaguar. Or, you could hit the hiking paths that weave and wind out of towns like Bullet Tree Falls and Spanish Lookout, past the sprawling citrus orchards and into the wild jungles of the Mountain Pine Ridge Forest Reserve. But that's not it, because this onetime stomping ground of the Maya has some formidable archaeological sites as well. Head to crumbling El Pilar or tree-shrouded Cahal Pech, and be certain not to miss the king of the lot, Caracol, with its stepped temples and mysterious tombs.