The only active volcano is on the Big Island. You will have to fly, then rent a car to see it. You should be aware that if Halema`uma`u is pumping out lots of vog it can affect your respiratory system adversely. I'd be especially concerned about seniors and kids.

Depending on how early you book, the plane could cost $200 or more per person round trip. If you're early enough and lucky it might only be around $125.

pzp is right on. You should also consider doing part of your time on Maui and then spend the other part on the Big Island if you plan on seeing the volcano. I've found that most visitors think the islands are closer together and smaller than they are. Each one has so much to offer, enjoy the island(s) you pick and save the others for another trip! Aloha!

When you say you want to see an active volcano, what exactly do you mean? An active flow or a smoking caldera? You can see a lot of interesting things at Volcanoes Nat'l Park on the Big Island, but getting close to the active flow is tricky and can be dangerous. And then there is the VOG issue that can be troublesome for anyone with breathing issues.

Maui to Hilo is going to cost $185 now PP....if you can find it for a rt...