With Granada's scorching summer heat, it can be a bit frustrating that the waters of nearby Lake Nicaragua are too polluted to swim in. But if you're desperate for a dip, salvation is near at hand in the form of Las Isletas, a chain of nearby islands where the water is just peachy.
The 365 islands that make up this chain were originally formed when Volcan Mombacho blew its top some 20 000 years ago. The volcano's massive cone was scattered into the lake, forming the rocky outposts you see today.
Of the hundreds of islands, the most visited are the Castillo San Pablo and the Isla de los Monos (Monkey Island). The former is an 18th century Spanish fortress, built to defend Granada from pirate attacks (which, incidentally, it failed to do). Monkey Island, as the name suggests, is an island that hosts a family of monkeys. These creatures are relatively friendly, but have come to see tourists as a food source so we'd think twice before disembarking – they can get nasty once you run out of goodies to hand out. It's fine to bring along fruit for the little creatures, which you can distribute from the safety of your boat. Across from Monkey Island is a popular bar and restaurant, complete with a sun deck and diving board. Many people use this as a base for swimming.
Most tour agencies in town offer trips to the islands, but if you're more than one person it will be much cheaper to arrange it yourself. Just take a taxi to the embarcadero (dock) for boats to Las Isletas. It should cost around 15 C per person, depending on your negotiating skills. These skills will be further tested once you embark, since you'll almost certainly be met by a tout offering three-hour island tours for $30. If you're two people or more, this will already be a steep discount on what the agencies in Granada offer, but you can negotiate it further. Viva's reviewer got them down to $23. Standard trips include visits to these three islands, with a break of about an hour at the restaurant to swim and eat, if you're so inclined. If you're not interested in the sightseeing, you can just ask them to drop you off at an uninhabited island, and return for you in a few hours. Bring food, water, and any other provisions you need and prepare for a relaxing day.
Another option is to head through the islands by kayak. Most tour operators in town offer trips, or you can rent one yourself from Puerto Asese, near the docks.