What country are you in? If you're in Canada I'd say to go over to TRU and get this: https://www.toysrus.ca/en/Mega-Fire-Boat-Playset---R-Exclusive/F518845B.html

Here's one I spotted that might be interesting: https://www.amazon.com/Popular-Playthings-60201-Magnetic-Build-a-Boat/dp/B000OP6W76

I think if you search for 'ocean liner' on AliExpress there's a few options that would pop-up.

Another avenue would be Playmobil. They even have a cargo ship https://www.playmobil.ca/en/cargo-ship-with-boat/70769.html

And they even sell an underwater motor compatible with any of their ships. https://www.playmobil.ca/en/underwater-motor/7350.html

Another toylike that has scale model of real ships is SIKU (the German Matchbox). They make a ton of die cast vehicle at various scale. I don't think they actually float though :p