The authors investigated on the boat basin, a facility of Yamashita Park that looked on Yokohama Port, by means of the literatures and drawings. The foreign residents brought various western sports and recreation cultures to Yokohama since the 1860’s. Sports, recreation with yacht and boat were made by foreign residents in old Yokohama Port. Yamashita Park, one of the urban parks during the reconstruction period after the Great Kanto Earthquake, was constructed in 1930. The boat recreation in Yokohama Port was permitted at that time. The boat basin of Yamashita Park was set up as a base of boat recreation in Yokohama Port, and as an entrance for boats on a disaster time. Another boat basin was made in Sumida Park, which was constructed at Sumida riverside, Tokyo in 1931. Yamashita Park was used as the site of Yokohama Reconstruction Memorial Exhibition in 1935, and the boat basin was turned temporary into a play boat pond. After World War II boat recreation in Yokohama Port was prohibited because of the navigation confusion. Therefore the boat basin of Yamashita Park was closed in the 1950’s. The site of the boat basin was filled up with earth, and remade into the symmetrical sunken garden.