Guatemala has a lot of volcanoes, many of them over 3,000 metres high.
Volcán de Pacaya 2500m - this is an active volcano about 30 minutes outside of Antigua. Some days it will not be accessible as the volcano may be too active to observe safely. Bring a jacket since it will be windy and cold at the top although the ground will feel warm and wear long pants as the volcanic rock can easily give you a nice cut. Tour guides can be organised from Antigua. Up until its most recent significant eruption in late May of 2010, you were able to walk right up to see real lava and even roast hot dogs and marshmallows over it. Although trips are still common and travel agencies still boast this possibility with pictures of tourist doing so in the past, this is no longer possible.
If you decide to travel to Pacaya alone the prices are quite reasonable. About GTQ50 USD6 entrance to the park itself. At the entrance to Pacaya National Park you will be required to have a local guide, licensed by the park to take you to the top of the volcano. There are two separate entrances to the park, the first located in the town of El Cedro and the second in the town of San Francisco. The El Cedro route is an easier climb, around 2 hours up & 1 hour down the volcano. The San Francisco entrance is a few miles further past El Cedro. It's a bit of a steeper climb. The entire park is patrolled by local police as well as soldiers...it is quite safe. Locals also offer horses to bring you for around GTQ125 USD15 which if you're not into hiking is a great alternative. These are offered to you when you begin your ascent. There are restrooms & snacks/drinks available for sale at both entrances as well. Secure parking is available for those travelling without a tour group.
Many companies offer this travel like: