The only bright side to all this, is that eventually there may not be a piece of the planet worth fighting over.
The first thing you notice as you descend, is the sudden peace. An absolute silence punctuated only by the sound of your breathing into the regulator and the air bubbles escaping into the surface.
As you descend, you start to notice a second thing: Blue. Lots and lots of blue. The vibrant color surrounds and engulfs you, with the sun rays piercing the surface occasionally.
As the last bit of air bubbles out of your BCD and you exhale slowly and calmly, the weightless feeling sinks in. The sound of your breathing and air bubbles makes a constant musical backdrop to the scene unfolding before you. As the pressure builds up while you slowly reach the bottom of the sea floor, you equalize constantly.
Once at the bottom of the sea floor, you check that your buddy is with you and you two set off in an adventure like no other.
The closest thing i can describe that is akin to diving, is flying. The weightless feeling, the sense of complete unrestrained movement and the gliding above the sea floor. This is what a bird must feel like when it flies: A sense of joy and unbridled freedom.
As you quest forward, the sea unveils its treasure to you. Fishes swim in schools, shimmering in vivid colors of red, blue and green. Stony corals placidly shelter teems of sea life while providing a fascinating background of colors and shapes. Soft corals wave lazily at you, while shy fishes peek out from their hiding places. Occasionally, a brave white fish will swim up to have a curious investigation of you before darting away.
As you glide along marveling at nature, fresh air is brought into your lungs steadily and reassuringly. You move along, trying to see as much sea life as you can. Constant monitoring of your SPG soon indicates that you don't have much air left. Reluctantly signaling to your buddy, you two head up to the surface, with the wonderful sights deeply embedded into your mind.
I'll be back, you fervently promise.