A term I have heard is the "water was like class". Meaning that the water had 0 waves. Could a rocket be modified to take off a horizontal surface starting slowly increasing throttle on each stage? First using hydrofoil skids which would release when the ground effect wings lift the rocket then dropped when the wings and air breathing stage when it no longer creates lift? Can more thrust come from launching parallel to water?
All the rocket would have to do is fly strait while the curvature of the Earth pulls away as the rocket slowly increases speed.
How much more thrust come from the Rocket exhaust being angled down into the water a little?