Everything is in the elevation.
I'm rather fit, used to be in the army nearly ten years ago. These days I hike now and then. Last weekend I went on a wee tip, 25 km and 1400 m elevation; it took me 9 hours, not including my lunch break. Only carrying water for the day, the said lunch, dry clothes and a bit of gear ; probably a 10 kg pack. Mild weather and decent track. On flat ground, I would have halved that time.
That just means you've invented a new fancy way to combat rising oceans!
(No, in reality, we have nowhere near the power to make appreciable amounts of hydrogen escape. Even if you electrolyzed water continuously with 2.5 TW of power, which is roughly global average electricity generation, you'd lose something like 4 cubic kilometers of water per year. The Earth meanwhile has over a billion cubic kilometers of water in its oceans, so you'd need over 250 million years to make them disappear.)
