The Alster Lakes are Hamburg's green and blue heart, consisting of two lakes: the smaller Binnenalster in the city centre and the larger Außenalster surrounded by ancient trees, parks, and elegant mansions. The popular 7.6-kilometre jogging path circles the Outer Alster. In summer, the surrounding parks are perfect for grilling, sunbathing, and water sports including rowing, kayaking, and stand-up paddleboarding. The lakes host events such as the cherry blossom festival and dragon boat races. The Inner Alster offers views of magnificent city centre buildings and the famous lake fountain.