Nectar

Most pets blink to you once you get far enough ahead. This one does not. It makes the whole trip under its own power, so a magic mirror, a teleporter or a long minecart line strands it wherever you left it and it slowly works its way back. If you want it on screen again immediately, cancel the buff and use the item again.

Water does not slow it down or drown it, though it still makes a splash noise every time it crosses a surface. Worth knowing if you keep it out during an ocean dive and wonder what the noise is.