What special things do I need for Alaska cruise?

I didn't take Gor-Tex but do pack an extra pair of shoes. Alaska cruises are very casual during the day. Jeans, hiking pants, boots, tennis shoes, sweaters, scarf, gloves. Dress in layers. On our first Alaska cruise we dressed for dinner, but a lot of people didn't. On our last one we did anytime dining and it was very casual. Bring binoculars for both your and your husband. No sharing. There has been several threads recently with lots of great hints. Enjoy! It's so beautiful there.

A lightweight rain slicker, somewhat oversized so that you can layer underneath it if necessary. In addition to the sweatshirt, add a scarf and hat. We visited the first week of July, and this Florida girl nearly froze for most of the cruise. Compact pop up umbrella, yet also sunglasses for the glare off glaciers if you take a glacier tour. If you have an exterior cabin, eyeshades for help sleeping at night. Before the cruise, I struggled to sleep in our hotel because it didn't get "dark" until almost midnight. Either leave space in your luggage or pack a lightweight duffel at so that you have room for souvenirs.

We went 5 years ago (and are going again this summer) and we had gorgeous weather, but I'm from Seattle so it wasn't too much of a temperature differece than what I'm used to. I did buy a knit hat on the ship for scenic cruising day because it was cold with the wind out on deck, but other than that I was fine with jeans/capris, wool socks, tennis shoes, and a hoodie. I'm sure I packed a warmer jacket, but I don't remember ever wearing it. Have fun!!

Skip the umbrella as you'll want your hands free for binoculars and camera. Just use the hood on your rain coat or bring a hat.

Bring a small binder clip to fasten the two sides of the curtains together. That will keep it darker in the room.

Enjoy!

My photo tip is to take a photo of the stop, for example, Skagway, before you start taking photos. Then you'll be able to go back and know where you were. Also, take a photo of the name of each glacier before you take the photos. This really helped me when I got home!

As above -- layers of clothing. You might need a heavier coat and mittens and a hat. If you are cruising only those will be less important because you can always pop back inside!
And you can't really anticipate the weather -- our 2nd cruise was in mid August and it had been VERY warm in Alaska. I didn't pack a warmer coat due to the previous temperatures. We arrived in Fairbanks and it was almost hot - short sleeves, capri and sandals weather. WE took a land tour to above the Arctic Circle and the weather was beautiful and warm - long sleeve T shirt and capris. The next day, the rain started and it turned VERY chilly -- so much so that I ended up buying a winter jacket and then really didn't take it off for the rest of the trip! It was COLD and rainy the rest of the trip!
For ports -- we brought several cheap rain ponchos (very inexpensive!) and kept them in their teeny little bag at bottom of a day bag. In Ketchican it was raining - not a gentle mist, but constant rain. An umbrella would have been a total PITA -- the rain ponchos were just right and when we got back to the ship (or stopped for lunch) we just ripped them off and threw them away -- and they were big enough to swoop over the original outerwear AND the day bag.
Binoculars for EACH person in the party -- critical.

I am not much on buying souvenirs. The thing I would suggest is that you look for authentic Alaskan goods.  Like most cruise ports -- much of the product are 'extruded plastic' from Asian mass producers. If you really want something .. look for something authentic to the region.

I had a lightweight windbreaker with a hood. I was able to wear it over my fleece when it was cooler.

We went in late August and experienced all 4 seasons!

The only souvenirs I recall bringing back were warm, knit socks. The photos of the bears, bald eagles, whales, seals, etc were the real souvenirs!

The whale watching excursion was excellent. The reason they have the money back guarantee is because you will see dozens and dozens of whales and much more.

DH and I took the kids on an Alaskan cruise last July. We sailed from Seattle which was really warm. It did rain a little bit, but that was while the ship was out to sea and there were plenty of inside things to do. We didn't pack anything warmer than sweatshirts and fall jackets which were needed while sailing through Glacier Bay and when we went whale watching. Never needed any type of boots, umbrellas or bug spray. The ship kept all the common areas heated so I never had to wear jackets while indoors. Our ship the Norweigan Pearl was VERY casual. They had 2 dress up if you want to nights, but very few people seemed to participate. Some people might not like the casualness of our cruise, but it was perfect for families like ours and there were LOTS of families onboard. We booked a couple excursions prior to leaving home and booked another while we were on the ship. Also the pools were heated so the kids, etc. had no problem swimming even when we were sailing through the cooler areas (of course mine could usually be found at the basketball court lol). My biggest tip is to bring post it notes so you can leave notes for each other on the outside of your cabin door. Helpful since you can't use your cell phone.