Boaco makes a reasonable base for exploring the surrounding highlands. The landscape is rolling cattle country with occasional dramatic terrain — not spectacular in the way that Pacific volcanoes are spectacular, but quietly pleasant and very different from what most visitors see of Nicaragua.
The Salto del Cuisaltepe waterfall is the most obvious excursion: a modest waterfall in the hills outside the city, reached by a short hike. It is popular with local families on weekends and is a pleasant half-day trip. Ask locally for current directions, as trails are not always well signed.
The Virgen del Chiquito chapel sits on a hilltop outside Boaco and is a local pilgrimage site. The walk up offers good views over the surrounding countryside and is manageable in an hour or two.
Further afield, the town of Teustepe to the south and the cattle towns of Muy Muy and San José de los Remates to the north and east give a sense of the wider Boaco department. None of them are destinations in themselves, but the drives are scenic and the towns are authentic.