SO Festival 2025 Lincolnshires Free International Outdoor Arts Festival across 2 seaside towns! Join us for SO Festival 2025, a vibrant 4-day celebration of outdoor arts across two towns of the Lincolnshire coast, Mablethorpe and Skegness. This free, family-friendly festival transforms the streets, parks, and promenades of Skegness and Mablethorpe into a dynamic stage for world-class performances.