1. Nevado del Ruiz is a stratovolcano located near the city of Manizales in Colombia. It is part of Los Nevados National Natural Park and is one of the highest active volcanoes in the Andes. The volcano has had several major eruptions, with the most destructive one occurring in 1985, when a mudflow caused by the eruption buried the town of Armero and killed over 25,000 people. Today, the volcano is closely monitored by the Colombian Geological Survey to prevent such tragedies from happening again.

2. The national park where Nevado del Ruiz is located is open to visitors, but the volcano itself is not accessible to the public due to safety concerns. It is recommended to check with the park authorities for any restrictions or guidelines before planning a visit. The contact number for Los Nevados National Natural Park is +57 315 8759085.

3. To visit Nevado del Ruiz and the surrounding national park, visitors can typically arrange guided tours through local tour operators in Manizales or nearby towns. The park entrance fee is usually around 10,000 to 15,000 Colombian pesos for Colombian citizens and residents, and around 25,000 to 30,000 Colombian pesos for foreign tourists. Transportation to the park can be organized through tour operators or by renting a car and driving to the park entrance. It is important to bring warm clothing and proper hiking gear, as the high altitude and cold temperatures can be challenging for some visitors.