Zooms. I went the used route and got a pair off Ebay, they were way bigger then what's available now, but I didn't care as I was only using them a few times a year.

You can spend a fortune, or you can spend not that much at all, if they are simply for the cruise and not for boating or anything where you need them every weekend, there's not a lot of reason to spend lots of money on them.

I say zooms because there are times you want to see a group of something on the shore, or the wall of a glacier, and there are times (early on in the cruise, as it gets old fast ) you want to zoom in on the dark thing way up on a tree to discover it's an Eagle in a nest.