Man from Atlantis (1977)

S1E7 Crystal Water, Sudden Death

In a bid to develop a satellite weapon capable of disrupting Earth's communication systems, Schubert sets his sights on harnessing energy crystals safeguarded by an underwater force field. These precious crystals are not only vital for his weapon but also serve as the energy source that sustains a hidden underwater civilization of humanoid beings. As Schubert's plans unfold, he unwittingly threatens the delicate balance of this submerged world.