Semuc Champey is one of Guatemala's genuinely unmissable natural sights — a series of natural limestone terraces spanning the Cahabón River, filled with crystal-clear turquoise pools at different levels. You can swim in most of the pools, wade between terraces, and look down through gaps in the stone at the rushing river far below. The setting is in dense cloud forest, and the walk up to the El Mirador viewpoint above the site gives a perspective on the full formation.
The pools range from knee-deep to several metres, and they are warm enough to swim in year-round. The site is managed as a national park with an entrance fee; a wooden platform at the top of the terraces and the Mirador viewpoint are easily reached in half a day. Most visitors combine the visit with a tour of the Grutas de Lanquín, the river cave a few kilometres before Semuc Champey on the road from Cobán.
The road from Cobán takes about two hours on poor surfaces; most travellers join a day tour from Cobán or stay overnight in the village of Lanquín, which is within striking distance.