We went to Skagway as part of a cruise. My wife and I had never been there before. We did this excursion with our friends, and we booked it through TripAdvisor and not the cruise line. My wife gets motion sick and was a little hesitant about doing this trip. Weather was great, clear and 60 degrees. You meet on Broadway St 1 block south of the main downtown intersection (across from the large really nicely painted public restroom building). It was 10 minute walk from our cruise ship.
They take the guests in a bus on a quick ride to their hangar where you get a safety briefing and then fit for the exposure suits. The exposure suits are nice and warm. You do not need to wear any extra layers underneath it. I recommend you take the balaclava and goggles when offered on the raft. It helps with the wind on the open water when going full speed. You bring your phone with you but they lock up all other items in the hangar. Then you walk to the raft at the dock about 100 feet away.
In the raft, you sit on padded seats with feet rests and hold onto a bar in front of you. It's like a bucking bronco machine or Avatar's Flight of Passage if you have ever been to Disneyworld. The tour takes 2 hours. I recommend you sit on the right side given the option. Most of the viewing is done from the right of the raft. They take you over to the right side of Lynn canal and stop at certain points of interest, then over to the left side of the Canal and back. We went maybe 5-7 miles from the dock and could see Haines, Alaska in the distance at the furthest point. We saw bald eagles, lots of harbor seals (moms and pups), and even some otters. No whales though. They also stop at a few waterfalls for photo opps. Very cool.
Captain Bremen did do a few "donuts" in the water at full speed to give us 360 degree views. My wife with the motion sickness did not care for that but didn't get sick either. The naturalist Alyssa was very nice and talked to my wife often and gave her tips to help her feel better. The captain and naturalist were quite competent and professional and made the experience wonderful.
Considering my wife's motion sickness issues and the fact that this was our first trip to Skagway, we probably should have done the Yukon Railway instead. However, this was a good alternative excursion and fun for anyone who wants to get up close and personal with some of the Alaskan wildlife.