"Wow, it's mostly water huh?"

"...yep"

"..."

3 hours would be an extremely fast ocean transit. One of the shorter routes across the Atlantic is East Canada to Ireland, a distance of about 3000km (https://en.wikipedia.org/wiki/Transatlantic_flight), so that would be 1000kph, which is basically the upper limit of subsonic flight (https://en.wikipedia.org/wiki/Mach_number#Classification_of_Mach_regimes).

I have serious doubts about the carpet's aerodynamic performance at that speed, and the ability of the passengers to stay aboard.

I expect that a more reasonable top speed is around 100kph, and even then the passengers are gripping the rug with all of their strength to stay alive, and there is so much noise from the air moving around them they can't possibly have any conversation. For 30 hours non-stop.