Been on several Alaska cruises and I can tell you, you aren't going to get very close to a glacier. At tops, a 1/2 mile but doubtful even that close. Too much danger if one produced a large calfing (some as big as the Empire State building)...lots of wave action even at a mile out. Still, the 70-200 or the 70-200 with 1.7 converter would be handy.
What you want to do is get near the fore deck early in the morning, just as the sun is rising when inside the passage...ooooh, lots of great wildlife, eagles, dolphins, orcas and the occasional whale. I've even seen bear and you'll be amazed at how close they come to shore in some places.
As to tripods, it depends on the ship but if the seas are calm and you're on the inside, a tripod will certainly help. I did a 3 second night exposure on the Allure of the Seas and it is dead on steady, perfect. I posted it on here somewhere.