Regenerative Rocket Landing
It takes SO MUCH energy to escape Earth's gravity, and that energy is totally wasted as heat on re-entry.
Recapture it! Send that rocket straight into a harness in the middle of the sea, that can capture the energy as the rocket hits, (granted at a (nearly?) impossible speed).
A series of webbing that is attached to pulleys that drive motors, or some such. No big deal.