At first instance it looks like an iguana and since this photo was taken near the coast of Pernambuco, Brazil it could only be the green iguana, but as you can see from the photo the reptile is black. Perhaps green iguanas can be black under strict circumstances, but I could not find any instances concerning that from a reputable source, only from some dubious pet blogs and it was due to the lighting, temperature and overall cage conditions. It's worth noting that there were multiple animals and they were all black. In response to tyersome comment, the picture was taken in summer so I'm gonna assume it was hot at the time, regarding the size it seems to have almost 2 meters. This has to definitely be from the Iguanidae family and it appears to share similarities with the green iguana but the color is off.