Nuphar submersa is a species of rhizomatous aquatic plant endemic to Japan.

[1] Nuphar submersa is a perennial aquatic herb with slim, branching, prostrate rhizomes.

The petiolate, narrowly ovate floating leaves have a cordate-saggitate base.

[2] The 2-3 cm wide, pedunculated flowers emerge above the water surface.

[1] The type species was collected by T. Shiga at an altitude of 240 m in Koshiro, Imaichi-shi, Tochigi prefecture, Japan on the 29th of September 2004.