The São Silvestre de Almeirim is a running race event scheduled for December 27, 2025, in Almeirim, Portugal. It features a certified 10 km course by World Athletics, with official timing at 5 km and 10 km marks, along with a Mini/Walk event of approximately 5 km.

This event is open to all runners, including various age categories such as Senior and Veteran divisions for both men and women, as well as juvenile categories for the Mini/Walk. The race offers a festive atmosphere suitable for fitness enthusiasts and families alike.