Typical Alaskan Gear
Clothing/Shoes/Weather Gear: No matter when you visit, bring layers of clothing. It probably won't be very warm but it definitely can be cold. Waterproof gear is the best...also good hiking boots or shoes that you don't mind getting muddy and have good traction for standing on the boats. There's a Helly Hansen store at the harbor and other places to buy gear in town should you need it.
Toiletries and Medical Supplies: Hotels have toiletries if you forget something. Also, there's a Safeway that has everything you might need. A bit more expensive than in Anchorage, but the prices aren't terrible.
Photo Equipment: Lots and lots of film if you're still using that kind of camera. Tripod, good lens. Spare memory cards for digital cameras. If you can't get your camera wet, bring some sort of waterproof covering for it
Camping/Beach/Outdoor Gear: Waterproof shell for tents, good anchors. Maybe mosquito netting though that's more of a problem in the interior. If you're camping in a remote area, have a place to store your food from bears
Miscellaneous: Again, for remote hiking and camping: get a good map from USGS and know where you are. Our cell phones worked until we were 30 miles off shore but we have Alaskan service, so check your coverage.
Luggage and bags: make sure everything, including backpacks and totes, is waterproof because it will get wet.
Clothing/Shoes/Weather Gear: definitely wear layers. Fleece is great when it gets cold and it dries quickly. Make sure to pack a windbreaker preferably with a hood and either rain or fleece pants and waterproof hiking shoes.
Clothing/Shoes/Weather Gear: Even in the summer, Seward can be chilly...meaning, you would benefit greatly from 'layering'. In the morning down near the docks, you can get a cool breeze off the bay, but once the sun peaks out, it warms up quite nicely.
Photo Equipment: Lots of film, this town has some beautiful sights, the scenery is great.
Miscellaneous: beware, you could run into a TSUNAMI!