Seen from the air, Ometepe Island looks like an hourglass as a slim isthmus connects the crater of dormant Maderas Volcano to the very much still active cone of Concepción Volcano. It was these volcanoes that inspired Ometepe's name, which is a local Nahuatl word that means "island of two hills."
Though a new airport is scheduled to open on Ometepe this year, most visitors still arrive by ferry across Lake Nicaragua. Also known as Lake Cocibolca, this 3,000-square-mile lake is the largest in Central America and was once filled with bull sharks that adapted to the freshwater conditions and became infamous man eaters. They ruled the lake until fishermen nearly wiped out the population for their fins. Hardy descendants still patrol around Ometepe.
The sight of the island's volcanic craters from the wind-swept waters of Lake Nicaragua inspired Mark Twain to write "they look so isolated from the world, so tranquil, so dreamy" as he traveled through the country in 1866. It's an observation that held true as I journeyed across Lake Nicaragua in 2012. Though Twain never laid foot on Ometepe, I did.
Surviving the island
In 2010, the same year the entire island was named a Biosphere Reserve by UNESCO, the producers of "Survivor" chose Ometepe as the location for the show's "Redemption Island" season. Contestants faced a number of challenges but none of them were as daunting as the No. 1 adventure on Ometepe island: hiking up 5,100-foot Concepción Volcano.
Concepción, one of the most active volcanoes in Nicaragua, has erupted more than 25 times in the past 130 years and puts out a nearly constant stream of ash as if reminding us that it's not done yet. Its summit is reached via a steep and exposed trail over frustratingly unstable volcanic scree; the round trip can take eight hours or more.
The 4,500-foot summit of Maderas Volcano can also be reached via a slightly less steep trail blessed with firmer footing and even some shade provided by trees and shrubs that have slowly reforested the slopes of this inactive volcano.
Ometepe is also home to a number of scenic waterfalls. The most popular, 160-foot-high San Ramon, is reached via a dirt road that was in such bad condition when I was there that I was advised against driving it even though I was traveling in a 4X4 truck. Once at the end of the road it's a further 2.5-mile walk to the waterfall over a rough and rocky trail. Your reward is an impressive cascade with an inviting swimming hole.
Get on a horse
A lower-impact way to explore Ometepe's natural attractions is on horseback. Hari's Horses ($8 per person per hour; www.harishorses.com), near the village of Balgue on the southeastern shore of the island, is owned by a guide and trainer named Hari who maintains a stable full of the most well-trained and well-fed horses I saw in all of Nicaragua. Hari offers scheduled and bespoke excursions for riders of all levels, including a four-hour trip to the San Ramon waterfall and a seven-hour ride around Maderas Volcano, which includes a swim in the lake with the horses.