Saltos del Monday, Nature reserve and waterfall in Presidente Franco District, Paraguay.

Saltos del Monday is a waterfall on the Monday River in Presidente Franco District, Alto Paraná Department, eastern Paraguay, about 10 km from the Brazilian and Argentine borders. It drops roughly 40–45 m over dark basaltic ledges in three main falls plus smaller ones, across a width of about 120 m. A 40 m panoramic elevator, inaugurated on 1 November 2015, links the top and bottom of the main fall, and a concrete pillar with a viewing platform stands at the right edge of the falls amid dense green forest.

The falls were one of the stops on the Tapé Avirú, the pre-Hispanic path used by the Guaraní. On 1 November 2015 a 40-metre panoramic lift, the highest in Mercosur, opened to carry visitors between the top and the base of the main fall. In 2017 the falls were named Paraguay's most popular attraction in a Vouchercloud map based on TripAdvisor data, and on 6 May 2018 the 800-seat Tape Aviru amphitheatre opened.

The name Monday derives from the Guaraní words monda (to rob) and y (water), often read as "water that robs" because crossing the current was dangerous. Since 14 June 2024 the Paraguayan government has officially called the falls Cataratas del Monday, replacing Saltos del Monday, since their size and flow exceed those of a salto. The Tape Avirú amphitheatre, opened on 6 May 2018, seats about 800 people for artistic and cultural events.

The park has multiple walkways and platforms that provide safe access to different viewpoints of the falls. It is wise to wear comfortable shoes and be aware of wet surfaces on the viewing areas, particularly if you plan to explore water sports activities.

The 9-hectare Municipal Park Monday holds the last remnant of the eastern block of the Alto Paraná Atlantic Forest, on the Paraná's western side. The 2016 Paraguayan horror film Gritos del Monday, by producer David Miranda, shot scenes inside the park.