The first day of Petropolis Teresopolis crossing is the most demanding. During the 8 km up to Castelos do Açu shelter we gain approximately 1100 meters of altitude. The trail of Açu mountain goes through a dense forest and with a strong ascent to Pedra do Queijo viewpoint. Then the trail gets a little less steep until arriving at Ajax viewpoint, which has natural water supply. After Ajax, we need to face the point considered the most difficult of the ascent to the Açu castles: the Isabeloca mountain. This ascent is named after an alleged passage of Princess Isabel on the spot. Once Isabeloca is over, we’ll cross the Chapadão do Açu, a counterfort, before arriving at the Açu castles. This is the first place to stay overnight and where the first mountain shelter of the Petropolis Teresopolis Crossing is located. The view of the Açu castles closes the first day with a golden key. From there it is possible to see all of Rio de Janeiro and Guanabara Bay in addition to the entire mountain range of Serra dos Órgãos. Hiking time: 5 to 7h Hiking distance: 09 km Overnight mode: Mountain Shelter at Castelos do Açú Peak Meals included: snacks, Dinner.