I will be starting a cruise in Seward, and I am planning in getting there a day early. Is there enough to do worth spending an extra day?

MORE than enough. My top recommendation is a Kenai fjords boat tour, you need at least 6 hours on the water but this is greatly superior to ANY wildlife or glacier views you will get from your cruise ship. Exit Glacier is worth a stop, doing the upper hike, really is worthwhile for the closeness to the glacier although has receeded significantly in the last few years. The Sealife Center is top notch there is a nice historic museum. Request their visitor guide www.sewardak.org

Vitally important with any Kenai Fjords trip, if prone to sickness TAKE PRECAUTIONS, I see sick passengers every trip, usually the ones at the dock who say they don't get sick.

I agree completely--those are the three things we did, and they were wonderful. Try to book the behind the scenes tour at the Sealife Center.

The Kenai Fjords boat trip is an absolute MUST as you are hearing here. I recommend the 9 hour one. Yes, it will take up your whole day there, but what fabulous trip it is. We saw everything we came to Alaska to see in that one day - orcas, otters, calving glaciers, puffins, humpbacks, sea lions, etc. And our guide was extremely knowledgable and fun. The food was really good also!

You should have time to do the Sea Life Center the morning you board your ship. And I agree with the recommendation to do the behind the scenes tour. It was really fascinating. Especially when we got to watch the live feeds from the island where the Stellar sea lions hang out and watch and orca circle waiting for one of the babies to come its way! Have a wonderful trip!