Our trip from Medan, Sumatra's biggest city, to the jungle takes about five hours, even though the distance isn't even 100 kilometers (62 miles). The roads are in such a bad state that it's one pothole after another. As a result, we're nicely shaken-up by the time we reach Bukit Lawang, a small village with simple houses. Behind it, dense and like a green wall, is the rainforest.

Up close to orangutans

Bukit Lawang is the gateway to the Gunung Leuser National Park. From here visitors begin their tour to the orangutans - one of Sumatra's main attractions. The park with its approximately 9,000 square kilometers (5,593 square miles) is one of the biggest intact ecosystems in Indonesia and one of the last habitats of the friendly primates. Orangutans were once indigenous to most parts of south-east Asia, but today they are threatened by extinction. You can only observe them in Borneo and in northern Sumatra.

Our little group led by knowledgeable guides makes its way into the muggy and humid rainforest. Just a quarter of an hour later, at the entrance to the park, we make our first sighting: a female orangutan is sitting comfortably in one of the high trees, languidly watching some tourists who are competing to take the ultimate picture. What we find particularly fascinating are the facial expressions of these animals. They seem both strange and familiar. Our Indonesian guide Indra explains that an orangutan genome is 97 percent identical to that of a human. It is therefore no surprise that the name "orang-utan" means "person of the forest".

Once the first snapshots have been taken we continue, going deeper into the rainforest. Indra points out indigenous flora and he also proves to have a good eye for jungle inhabitants. We discover black gibbons swinging in the treetops. Cheeky macaques skip fast as lightning from branch to branch. In comparison, the Thomas langurs with their distinctive Mohawk hairstyles appear stoic.

Still, the orangutans are the main attraction. During our two-day trek we were fortunate enough to be able to observe about 10 of these impressive creatures. 

The Bataks are a Christian minority with their own culture

Following these first impressions we continue on towards the uplands. That's where the indigenous Batak people live, a predominantly Christian group in the midst of mainly Muslim Indonesia. They speak their own language and still maintain many ancient rituals and traditions.

Their architecture is particularly impressive. It can be admired all around Lake Toba. As far as the eye can see, the upsweeping roof ridges of the traditional Batak buildings stretch into to the steel-blue sky. The mayor of a small village explains this unusual design. The three levels of the building symbolize the ancient beliefs of the Batak in how the world is divided: the substructure of pillars remains unused and represents the underworld. Above it is the living area, which is the sphere of man. The airy roof remains empty and its use is reserved for gods and ancestors.

Banda Aceh is a living reminder of a catastrophe

The last stop on our trip in Banda Aceh, up in the far north of Sumatra. The provincial capital seems friendly and open and can be easily explored on foot. This place however is still closely associated with one of the most devastating natural catastrophes of recent times: the devastating tsunami of 2004.  In Banda Aceh alone, some 25,000 people were killed and in the entire region more than 170,000 died. Today, at first glance, little can be seen of the destruction. Remembrance of the catastrophe on the other hand is unavoidable. The Tsunami Museum, which opened in 2009, gives you an insight into what occurred.

The entrance to the museum leads through a dark tunnel. Water runs down the walls, which are 22 meters high - the same height of the wave which rolled over the town on December 26, 2004. While we walk along the tunnel, sound effects of surf and voices cause a sense of disorientation. This just gives us a small insight into what the situation must really have been like for those affected.

A memorial about one kilometer away from the museum also commemorates the natural catastrophe. In the middle of the town on dry land you'll find a ship, which weighs several tons, looking like a stranded whale - a surreal sight. The tsunami pushed the 60-meter hulk some five kilometers inland, right into a residential area. And yet, despite all that has happened, life goes on - here as well.