The main area of interest here is the massive Santiago crater that was created between the Nindiri and Masaya volcanoes. Eruptions took place frequently during the 1900s until the crater eventually collapsed in 1985. The result is bellowing sulfurous gasses and the sound of thunderous lava flows rocketing beneath the crater hole.
The tour starts with a visit to the cross (La Cruz de Bobadilla) overlooking the volcano and the surroundings. Next you see the magnificent Green Parakeets that return to the volcano every night to roost. These birds have somehow become adapted to the sulfuric fumes expelled from the volcano and actually live within the crater.
You also observe a large number of bats departing their caves, another great natural spectacle, then proceed to an underground tunnel that has been formed by streams of lava. Equipped with flashlight and helmet, you can enter the tunnel and observe the interesting rock formations.
The trip ends with a visit to a viewpoint that provides the opportunity to look inside the crater mouth of the volcano, observing the glowing lava.