Verb conjugation of "contaminar" in Spanish

I ordered a cab at four o'clock in the morning which took me to the Central Bus Station. I was much to early because the bus would go just at seven o'clock. Anyway I was sitting there and listening to music.
The trip included a lot of walking and the guide told us the history of this region, of the Chiapas state and also how it evolved in the context of the entire Mexican country. Very interesting!!!
I chose a room in the center of town. I went to the northern beach of the island which was supposedly the most beautiful one. There were many young tourist lying in the sand but I still felt foreign.