Add or make more items in the game such as, different fins like sub 1 and different body suits that add armour, or a weighted suit so you can walk on the sea floor. Light Spectrum Projector
A lamp that produces different wavelengths instead of just white light.
Some plants might open under ultraviolet light, reveal hidden patterns under infrared-like wavelengths, or release nutrients when illuminated in a particular sequence. Predators could also react to specific colors, making lighting a stealth mechanic.