Helsingborg Marathon was born in 2014 and quickly became one of Sweden's leading marathons; in early September up to 3,000 runners line up for the marathon, half marathon and relay on a World Athletics-certified course. The single loop starts at Sundstorget, follows the sea and harbour with views across to Denmark, then takes in the Ättekulla nature reserve, Ramlösa spa park, Fredriksdal open-air museum and the medieval Kärnan tower. Its trademark is a passage through the indoor Helsingborg Arena, billed as the first marathon in Europe to go indoors. The final kilometres run along the water to the finish at Gröningen. Helsingborg offers Sofiero royal summer palace and gardens, a 20-minute ferry to Helsingør and Kronborg Castle in Denmark, and waterfront cafés.