Scrub and coarsely grate the beetroot. Zest the oranges. Slice the white pith from the oranges and discard it. Halve the oranges and flick out any pips. Slice 1cm off the ginger (although you can use more if you like it fiery).
Add the beetroot, oranges and ginger to the blender with a cupful of ice. Pour in the coconut water. Blitz till smooth, adding a splash of ice cold water if necessary.