About 8km (5 miles) south of Cobán sits the town of San Juan Chamelco, home to a colonial-era church and gateway to two popular local attractions: Grutas del Rey Marcos, a small cave system, and Balneario Cecilinda, a complex of natural spring-fed pools.
The Gruta del Rey Marcos features beautiful stalagmite and stalactite formations. Some of these are very large; one has even been dubbed the Leaning Tower of Pisa. At one point you'll have to ford a small river to get to the more impressive cave galleries.
If the weather's nice, you'll definitely enjoy a dip in the pools at the Balneario Cecilinda, which are very popular with locals, so expect to meet many if you come on a sunny weekend.
If you want to stay in the area, check out Don Jerónimo's (tel. 502/5301-3191; http://dearbrutus.com/donjeronimo), a delightful and rustic joint with a gregarious owner who knows the area well. This place specializes in ecological and spiritual vacations or retreats, and serves up tasty vegetarian cuisine. Don Jerónimo's is located 1km (less than a mile) before the Gruta del Rey Marcos.