Plans are afoot to build an 800-m swimming pool in the Dotonbori Canal in Osaka, Japan, according to a report in the Japan Times on Wednesday. If it opens as planned in mid-2015, it will reportedly become the world's largest outdoor swimming pool (though almost certainly incorrectly – see the update below).
The scheme is reminiscent of YN Studio's plan to introduce a commuter swimming lane, dubbed the LidoLine, into London's Regent's Canal. The idea is to drop a 12 m (40 ft) wide tank into the canal, and fill it with treated water from the city's water systems rather than using filtered water from the canal.
According to The Times, the scheme, which has been circulating for years, is said to be the idea of Taichi Sakaiya, former head of the Economic Planning Agency. The pool would be a further boost to ongoing efforts to gentrify the Dotonobri district, which Times writer Eric Johnston says has undergone renovation in the last 10 years, with family-friendly businesses supplanting "more risque establishments."
A private firm, Dotonbori River Poolside Avenue was formed in April to realize the project, which is projected to cost ¥3 billion (about US$490 million). Apparently no public funding is to be allocated.
Update: Readers are quite rightly questioning the claim that this is the world's largest pool. The 800 x 12 m dimensions gives an area of just under 1 ha, meaning the pool is dwarfed in area by, and also shorter in length than, the 8-ha pool at the San Alfonso Del Mar resort. This article and its headlines has been updated to reflect this.
Source: Japan Times via Wired UK
http://en.wikipedia.org/wiki/San_Alfonso_del_Mar
AFAIK the largest outdoor pool today is part of "San Alfonso del Mar" in Chile, with 80,000 square-meters and a length of 1,013 meters. The public pool in my hometown (Fürstenfeld, Austria) is deemed to be the largest one in Europe, with 23,000 square-meters.