I was in ISP at the end of the first season, and you will find it different from most ports you frequent on a major cruise line. First, you are on an island that has one town of Hoonah, which has about 850 residents. Many of these work for the native organization that runs ISP for the cruise lines. They are currently allowing only one ship per day and expanding from just Celebrity or RCCL to include a few others. Most of the services available are run for the cruise tours. There are a few fishing charter boats for hire for fishing or whalewatching. There are also a few locals who will do private guiding in boat or on land.
There are a few buses that will go into Hoonah, about a mile or two from dock. There may also be a few taxis. You can walk into town or along the local trails or waterfront area. If you are looking at the cruise excursions, you will see that they offer whalewatching, fishing, bear viewing tour, nature tour/town sightseeing bus, and native dancing. There isn't a whole lot more.
Without an excursion, your options are very limited. Icy Strait Point itself is quite small, and the nearby village of Hoonah doesn't take long to see. This area has some of the best whale watching in Alaska, so that's what I'm doing in late May ( with FISHES - http://www.explorenorth.com/library/...ka/hoonah.html ) I'm also going whale watching in Juneau and Sitka - some folks might think that's overdoing it, but marine laife is my priority, and every trip is unique.
Icy Striat Point is a recreated tourist area of it's own business entity, that employs natives. It is a former salmon cannery, not tuna.
It is located in the city of Hoonah. There is a bus that does go outside of this area for a fee.
There is plenty to do. The museum is free, nice loop walking trail. But also consider independents (was told by 2 locals that commissions for operating out of Icy Strait Point is 60%)