Just a couple of questions about the HAL Tracy Arm excursion that boards directly from ship:   1)  The HAL website states a "Starting At" price for this excursion.  What will drive the price up? 2)  In very late May/very early June, how likely will the excursion be cancelled due to icy waters? 3)  What's the approximate number of passengers allowed? 4)  Does it normally sell out?