These are 5 position alpha-numeric codes comprising the d series. All other level II codes and descriptors are approved and maintained jointly by the alpha-numeric editorial panel (consisting of CMS, the Health Insurance Association of America, and the Blue Cross and Blue Shield Association).
Alaska: Although Alaska enjoys a high volume of aurora activity, its cruises are not often mentioned as northern lights cruises. During the Alaska cruise season, it's rarely dark enough for the lights to be visible.
The best time to cruise to Alaska will vary depending on your preferences for viewing wildlife, fishing, bargain-shopping, sunshine, warm weather and catching the northern lights. Alaska: June through August. Australia: late November to March. Bermuda: June through August. Canada/New England: September and October.