Kai-Delvha Lifters

massive cargo-haulers, magically driven that sort of mostly levitate above the water with only a huge keel trailing in the sea

the keel lets the boat's magic work water magic to read the leylines on the sea floor whilst the main drive and lift is provided by air magic

so basically the ship just automatically follows the leylines (which it seems logical to me, flow between gates) allowing them to navigate the maze-like nature of the plane without having to know it well

basically it's a big, automatic cargo ship with a minimal crew hence real pirate bait

probably there has to be a fire component to keep the air spirits in check, just as they keep the water ones in check

so perhaps the ship is controlled by a fire mage?

who can double as a key element in its defense, along with the elementals themselves

the main drive is from earth spirits pulling along the leyline, while the air spirits mainly just lift and do fine adjustment it can also hover along out of water or not on leylines, but that doesn't work as well and is much, much slower - basically just for docking

but I kinda like the idea that the docks at either end are actually dry, it's just Anna's plane in-between that actually has water