Be careful, be very careful!
Many US insurance policies do not cover illness or accidents outside the continental US.
Plus....in the event of an injury, your medical will not cover the $35,000 air evac. It will not cover getting your family home. It will not cover a ton of stuff.
Of course, nothing will happen and you will have "wasted" $150 bucks.....but one never knows....we were not believers until we got the coverage and needed to use it...due to an illness PRIOR to the cruise...NOT covered by Blue cross. Blue Shield....now we never leave home without it