Beyond Acuaducto Los Arcos [1] is the approach to La Piedra de Apagüiz, a nearby mountain that can be hiked up in a couple of hours. Another worthwhile day hike is to Montaña San Cristóbal, about 10 kilometers outside Danlí [2], a short car ride or one-hour walk to the base of the mountain. Take the road to Mineral de Agua Fría and ask around for the trail. Continuing on this road will bring you to the ruins of the Agua Fría mines.
Links:
[1] http://www.moon.com/destinations/honduras/southern-honduras/department-el-paraiso/danli/sights
[2] http://www.moon.com/destinations/honduras/southern-honduras/department-el-paraiso/danli