Just to try to clarify a bit....
The OP is looking to book a cruise with a company called Innersea Discoveries.
They are an outfit that uses small boats - 40 to 60 people.
Most of the activities are pre-planned, and launch from the boat itself - things like sea kayaking, snorkelling, taking a zodiac to shore, whale watching from a zodiac, or going on a 5 mile hike, etc etc.
Pretty much every day, you'll be wearing a wetsuit.
Their cruises are not like Princess, or HAL - rather, their slogan is "The UN-cruise".
And it sounds like the activities might change day to day, based on the desires of the passengers that day.
Because of that, it means the demographic of the passengers is actually quite important. If the OP wants to go on a strenuous sea kayak adventure, but no one else on board wants to go, then the sea kayaking might get cancelled in favour of a one hour nature walk. I'm not saying this happens (I've not even been to Alaska) - rather, that's the concern of the OP.
The OP found a review on CruiseCritic (I've seen the same review) where someone claims they went on one of Innersea Discoveries cruises, and found that all the strenuous activities (which they were looking forward to) got replaced with "walk in the park" activities. Personally, that review sounds very much like someone with a hidden agenda. But the OP is young and is looking for strenuous, adventurous, activities. They're concerned (because of the review), that Innersea Discoveries might change their activities from strenuous to relaxing (not something they'd want).
The OP is looking to hear from people who have sailed with (or know people who have sailed with) Innersea Discoveries to hear what their actual experiences turned out to be.