Liu Zhi was inside the Death Star Ship, so he had no idea how it accelerated.
If he had seen what was happening, he would have been absolutely stunned.
As the Death Star Ship began to accelerate, it started sinking from its original position, where it had been floating about a meter above the surface.
Jets of air blasted from the vents on both sides of the Death Star Ship, driving up the water alongside it. When the ship sank to about a meter beneath the surface, the water thrown up by the jets formed a seawater tube along either side of the ship.
The tube was like the curling wave you encountered while surfing, wrapping the Death Star Ship inside it.
Then the jets on both sides of the ship began pushing the air backward, expelling all the air inside the tube.
The whole Death Star Ship now felt like a magnetic levitation train running in a vacuum. Inside this tube of seawater, it would meet no resistance.
That was why, when the Death Star Ship began to pick up speed, Liu Zhi and the others felt a powerful shove in their backs. They nearly went flying from the inertia.
The force of the acceleration made Liu Zhi understand why they had needed half an hour to prepare beforehand, and why everyone had to sit in their assigned seats.
The Death Star Ship's acceleration was nothing like what he had imagined—not merely a rise to ten or twenty knots.
From that brief burst, Liu Zhi had already estimated that the Death Star Ship was traveling at no less than three thousand kilometers per hour, more than twice the speed of sound. Even with the ship's interior designed for safety, accidents could still happen.
That was why strapping everyone into