The Triathlon of Fontelo is a triathlon event taking place on October 11, 2025, in Viseu, Portugal. It features a Campeonato Norte Jovem (Northern Youth Championship) and an Open Race, with distances adapted for different age groups, ranging from very young categories with short distances to juvenile and cadet levels with longer segments.

The event is open to all interested participants, with specific eligibility set by age and licensing for the youth and open categories. It is part of the national triathlon calendar and includes official classifications for individuals and teams, making it a competitive and structured race within the Portuguese triathlon federation framework.

The race courses include swimming in a 25m municipal pool, cycling on a mixed terrain circuit of dirt and asphalt in the Parque Desportivo da Mata do Fontelo, and running on asphalt and tartan track. The event offers a friendly but competitive atmosphere, catering primarily to youth athletes but also welcoming open category participants, with well-organized support and facilities.