The next couple airports in Japan to be built were built over water on artificial islands:
Kansai International: https://en.wikipedia.org/wiki/Kansai_International_Airport
Kobe: https://en.wikipedia.org/wiki/Kobe_Airport
Kitakyushu: https://en.wikipedia.org/wiki/Kitakyushu_Airport
Chubu International: https://en.wikipedia.org/wiki/Chubu_Centrair_International_A...