León was originally founded in 1524 by Francisco Hernández de Córdoba in the foothills of Volcán Momotombo. The volcano proved to be a volatile neighbor, and after a series of earthquakes and an eventual eruption in 1610, the Spanish were forced to move 30km (19 miles) east and reestablish the city where it now stands. The old city lay lost and covered in ash until it was rediscovered in 1967. Excavations have revealed a fascinating site, including the headless corpse of Hernández de Córdoba beside the remains of his executioner Pedrarias Dávila. The founding Spaniard was punished for insubordination. León Viejo, a neat collection of brick walls and pillar stumps, is now a UNESCO World Heritage Site, with spectacular views from the surrounding hills. It makes for a great 1-day tour and can be organized by most travel agencies in León city. If you would prefer to go there independently, catch a bus to La Paz Centro 3km (1 3/4 miles) east of the city. There you catch another bus to Puerto Momotombo 15km (9 1/4 miles) away. Be aware that the last bus returns from the ruins at 3pm. Vapues Tours and Grayline Tours conduct tours of the ruins. On-site, there is a small Visitor Center (no phone), and local English-speaking guides will take you around for a small fee. Admission is C44 adults; C88 if you bring a camera, and C160 if you bring a video recorder. The ruins are open daily from 8am to 5pm.
Los Hervideros de San Jacinto
Hervidero means "hotbed," and that description is no exaggeration when it comes to this ragged patch of land, 25km (16 miles) north of León. Los Hervideros de San Jacinto is basically a field of boiling mud, with steam rising from thermal vents and hiding the nearby peak of Volcán Telica. The bubbling muck is literally too hot to dip your hand into, though apparently it's very good for your complexion once it has cooled down. There are absolutely no tourist facilities here (though there is talk of the inevitable luxury hotel), and the site itself is not pretty -- but it is fascinating. The mud patch is close to the town of San Jacinto and is a good 1-day excursion from the city. Quetzaltrekkers (tel. 505/2311-6695; www.quetzaltrekkers.com) and Big Foot (tel. 505/8636-7041; www.bigfootnicaragua.com) will help you organize an excursion there, or you can just take a taxi or bus to the town of San Jacinto (take the Estelí or San Isidro service). The entrance has a large arched gateway where there are street vendors and guides.
Isla Juan Venado Wildlife Reserve
Have you ever wanted to see a mangrove warbler? Perhaps that's not on everybody's list of things to see, but this small yellow bird can be found only in mangrove swamps, and such a place exists on the Pacific coast west of León, just south of Las Peñitas. Isla Juan Venado is a 21-sq.-km (8-sq.-mile) wetland reserve that you can explore by boat or kayak. Here, you'll find pelicans and herons stepping over crocodiles, iguanas, and caimans in a labyrinth of channels and waterways. This is also an important turtle-nesting site, where thousands of turtles hatch. Tours can be arranged with operators in the city, or you can go independently and hire a boat in Las Peñitas village. There is an entrance fee of C40.