A free node to be deployed underwater for omnidirectional energy and data harvesting includes a housing that forms a sealed chamber; a wavelength-changing layer attached to an outside of the housing and configured to receive a first optical signal having a first wavelength range and to emit a second optical signal having a second wavelength range, different from the first wavelength range, wherein the first optical signal includes encoded data; a flexible solar cell wrapped around the housing, the flexible solar cell being configured to receive the second optical signal and generate an electrical signal; an energy storage module located in the chamber and configured to store electrical energy associated with the electrical signal; and a decoder located in the chamber and configured to receive the electrical signal and decode the encoded data. The first wavelength range is ultraviolet light and the second wavelength range is visible or infrared light.