These larger ships are at present allowed to visit Antarctica but are not allowed to land passengers. The current limit is 100 passengers landing ashore at a time so landings are impractical for the larger ships that now carry hundreds or thousands of passengers. Smaller ships will still be able to make an Antarctic cruise, land 100 passengers but must carry and operate entirely on MDO. Larger ships could of course carry only and operate on MDO but would still not be allowed to land passengers. One of my former companies Holland America Line (HAL) is planning to do just that.