Underwater scene = you will be able to see the beam of lights. You need to put volume light on the lights.
Your lights are Way Way to harsh. Subtle light goes a long way, tone down the multiplier of the lights and put attenuation on them. Also there is no style or color to the scene at all. Its just blue, thats very boring. Put some more colored light in other places. Like the background. Think of it like your lighting a stage. Experiment with light but keep in my that subtle light is better than bright lights.
I can't see the source of the white lights that is lighting up the hot air balloon looking things, you need to put that in.
Right now it looks like it could be a foggy night in on land. You need to put sediment that is floating around the place. This can be done with a particle cloud. Just turn the speed of the particles to zero or .01. Adding fish and bubbles would sell the idea that it is underwater. But the key thing would to add a projection map that fakes the light being refracted through the surface of the water. Like in this picture.
You have green glowing things at the tips of those spikes. I'm assuming they are lights. So they should cast a subtle amount of green on the surrounding objects. You need to put that in.
Your choice of composition is very confusing. I don't know what I'm suppose to look at. And none of it is arranged in a appealing way. You need to think what these things represent. Are they powerful? if they are put the camera at a low angle. That will make them more epic. The angle you have the camera right now portrays nothing about the scene. I really don't know if I'm suppose to look at the balloon looking things or the grid thats on the ground. The height and the angle of the camera makes me feel like I'm gonna fall off a railing.
Ok now were back to lighting. I would suggest lighting the side of the balloons (if they are your subject matter) with some Subtle green light. just so this scene can have some color in it. I would also dimly light the generators in the background with some Red or Purple light. Make subtle changes. Not drastically CG ones.