Long ago, reed beds, tidal flats, and shallow sea stretched across the area surrounding Edo Castle, and there was little even ground for people to live on; the area from today’s Hibiya to Otemachi was once known as Hibiya Bay, while what is now the land from Nihonbashi to Yurakucho was a sandbar called Edomaejima. When he moved to Edo in 1590, Tokugawa Ieyasu immediately set about filling in the tidal flats and shallow sea of Edo Bay and engaged in urban development focused on the use of waterways for transportation. The land reclamation conducted during the Edo period crossed over the Sumida River to reach 2,700 hectares of land. This is equal to the total area of the Shibuya and Chiyoda cities. Channels for rivers and canals were built to smoothly transport goods over water, resulting in the rapid growth of Edo to become one of the largest cities in the world with one million residents living inside its borders by the end of the Tokugawa shogunate government.
In the Edo period, a time when no air conditioners or refrigerators existed, the people of city sought out cool breezes in the summer; they would cool themselves in the evening on the banks of the waterways which crisscrossed the capital and play in the waters of the Sumida River.
In Edo, summer officially began with a festival on the Sumida River marking the start of the boating season (on May 28 per the old lunar calendar; June 30 using the modern calendar). Today, fireworks are a summer tradition in Japan, and this too began in the Edo period. The very first fireworks display held on the Sumida River was conducted in 1733*, and ever since then fireworks have been a customary part of the Sumida River opening festival.
Boating was a particularly popular activity during the Edo period. In addition to being used to enjoy the coolness of the river on summer evenings, boating was popular no matter the season, being used for cherry blossom viewing, moon viewing, and even snow viewing.
This Edo tradition continues to be passed on; even today, people enjoy riding water busses on the various Tokyo Waterway Lines. The water busses connect to locations such as Ryogoku, which offers a splendid view of Tokyo Sky Tree and contains the Edo-Tokyo Museum and the Ryogoku Kokugikan; Asakusa, home to the Senso-ji temple; the Hama-rikyu Gardens; and Odaiba Seaside Park.
