What else is walkable from here for 1 1/2 year olds?

From the aquarium almost everything in town is walkable. There is the Ripley's odditorium as well as the Guinness world records exhibit and about a dozen candy shops. Keep in mind that none of the attractions are geared towards children of that age but entrance fees for people under 4 are generally free.

Everything is walkable, but if it were me, I would make a stop in pigeon forge for an almost 2 year old. Maybe DollyWood. After the Aquarium there isn't much for a child that young in Gatlinburg...

Anakeesta is just across the street. There are a ton of arcades, shops and other touristy type things all within walking distance. Unlike Pigeon Forge where everything is spread out, you can easily walk just about everywhere in Gatlinburg.

They've all answered appropriately, all of the things in the area are geared towards older children and adults. It's mainly shopping and Ripley's. Ober Gatlinburg is mostly rides, but again, mostly older children type.

Depends on what they enjoy

We went to the mall across the bridge. It has a candy store in it. Most of the other things are further away.

Nothing for that young of child.