Most travellers see Lake Nicaragua from one of two bases: Granada on the northern shore or Ometepe Island in the middle. From Granada the easiest day trip is a panga boat through the Isletas de Granada. With more time, head out to the quieter Zapatera Island.
On Ometepe, the two volcanoes — Concepción and Maderas — are the headline acts, both serious all-day climbs. Easier days are spent at Charco Verde lagoon or seeking out the island's pre-Columbian petroglyphs.
The lake has two further oddities worth knowing about: its bull sharks, which still swim up the Río San Juan from the Caribbean, and the remote Solentiname Archipelago at the southern end of the lake, a long boat ride from anywhere but worth the effort for its naive art tradition.