Does anyone know if binoculars are available to use or rent on the Alaskan sailings?
On the ship itself, no. On some of the excursions, binoculars may be provided. For example, our whale watching excursion boat had binoculars you could use. It varies from excursion to excursion.
If not, what type of binoculars do you recommend that I pick up for the trip?
I did a bunch of research, and bought binoculars for our whole family last summer for our Alaska trip, so I'll share the high points. The short answer is Bushnell H2O (or Bear Grylls) 8x25 compact waterproof ($40) or 8x42 or 10x42 compact roof prism waterproof ($100) is what we ended up getting. I got one pair of Bushnell Legend Ultra HD binoculars for myself as an indulgence (they're $200), and the contrast was so much better than the regular Bushnells that I ended up getting another 10x25 Legend Ultra HD as my go-to compact binocular. I also had a big pair of decent Russian 7x50 binoculars for whale watching from the verandah and deck (they're pretty big to carry on an excursion).
The numbers on binoculars are the magnification and the objective lens diameter. So an 8x25 has 8x magnification and 25mm objective lens (the lens furthest from your eyes).
Higher magnification is generally good, but it becomes very hard to use a pair of binoculars when the magnification goes over 10x; your hand shake is heavily magnified and the field of view gets pretty narrow, making it hard to find what you want to look at. So 8x and 10x are the most useful and the most popular. 8x is a great intro magnification, and 10x is better once you get good at using them and finding the target quickly (see below for important tip).
Higher objective numbers are good because larger lenses bring in more light and increase the field of view. More light means you have a decent shot at seeing wildlife in the shadows and seeing whales at dusk and so forth. But bigger lenses increase the size and weight of the binocs. Anything smaller than 25mm is going to have too narrow a field of view to be usable and only be usable in bright sunlight. Anything bigger than 42mm is going to be pretty bulky. As I said, we did bring a 7x50 porro for ship viewing, and we used them a lot. The low magnification and high brightness made them great for grabbing off the desk and looking at wildlife and scenery quickly. But they're big. You could certainly bring them on a hike if you had to, but even the 10x42's felt a little bulky after hiking a mile or two.
Roof prism binoculars are lighter and straighter. Porro prism binoculars are wider and heavier, but slightly cheaper for a given level of quality. I decided if we were spending thousands of dollars to go to Alaska I could spring for roof prisms. And that's also how I convinced myself to get the Legend Ultra HD binoculars.
Waterproof is important for situations where you're around water and might get some rain or spray, which describes just about everywhere in Alaska.
So if you have the money, get a pair of 10x42, 8x42 or 10x25 Bushnell Legend Ultra HD binoculars. They're about as good as anything out there. Super sharp, super contrast, light, waterproof. The bees knees. But the Bushnell H2O 8x25 8x42, or 10x42 are also good and a lot cheaper. The Bear Grylls versions are identical optically to the H2O models, but have orange trim and the Bear Grylls logo on them. I'd get whichever is cheaper.
And here's a useful tip I learned from a National Park ranger (who carried Bushnell Legend Ultra HD 10x42's): when looking at something through the binoculars, the novice tendency is to look down at the binoculars as you bring them up to your eyes, and then hunt around for the target while looking through the binoculars. Instead, look directly at the target, and without moving your head or eyes, bring the binoculars right up to your eyes in one smooth motion. If you manage to keep your focus on the target and not move your head, you should be looking directly at it. If not, take the binocs away from your eyes, re-locate the target and try again until you can bring the binocs to your eyes without moving your head or looking away from the target. This is just a fantastically useful technique; practice it at home when you get your binoculars. It saves you so much time trying to re-find the thing you're trying to look at.
Hope that helps!
Don