{{asof|2002}}, the largest offshore structure built is theA ''Mega-Float'', a [[floating airport]] prototype that was constructed in Tokyo Bay from 1998 to 1999.<ref>[http://www.build.new-atlantis.org/vlfs.htm Very large floating structure — Mega-Float, completed 1999]. New Atlantis 2002, retrieved 1 October 2011</ref> It iswas one kilometer in length, and was primarily intended as a test vehicle, to research the loadings and responses of such installations.<ref>Areas being studied in Mega-Float include the hydroelastic behavior of the unit, the mooring system response and durability, the connector system and its welded joints, the anti-corrosion system, the unit's effect on the surrounding seawaves which impact the nearby shoreline, and the unit's effect on the bay's prevailing currents, water quality and marine ecosystems.</ref> This project was substituted as a study project to provide more definite information about a proposed floating runway at [[Kansai International Airport]], which was not built (an artificial island was instead constructed to support the runway).
