Achilles Injury, Cardio Alternative?

Well…didn’t think it would happen, but it did. Of all places for it to happen, it didn’t happen while working out, it was while I was at work and walking around. I injured my achilles tendon and have a long recovery to go. Before I injured it, I was doing 15 minutes or so of cardiovascular before my main workout. Since I am not going to be doing anything strenuous until it recovers, I was wondering if there was an alternative cardio I could do without putting undue stress on it.

Airdyne bike (use arms more than legs), battle ropes, rowing machine

Air Dyne and UB Ergometer are the obvious ones. I’m sure there are all kinds of weird machines that populate “regular” gyms so just give 'em a try.