 The city 's sandy fresh water beaches are a popular tourist attraction , while the sheltered harbour houses <unk> for recreational sailing . Since 1925 , the 400 km ( 250 mi ) Mackinac race from Sarnia / Port Huron to Mackinac Island at the north end of the lake has been the highlight of the sailing season , drawing more than 3 @,@ 000 sailors each year . 
