Sounds wonderful!

Honestly, I'd bring both. Not all landings are the same, and not all hikes are the same. But the wrong shoes can ruin a trip. Whatever you choose to wear on your feet, make sure they are blue. HAHA

In Hawaii last year, I used keens water shoes for my water trek/kayaking then hike shoes. they were perfect!

I've always wanted to go there. Anywhere you're going to be near water, water shoes are a must. I have no idea about other shoes. :) Have fun!!

I like my Teva Womens Hurricane Drift Sandals for "your feet might get wet" situations. They are one piece molded synthetic. Super ligthweight and the velcro is really strong. They have decent arch support so are good walking sandals too. I got mine on the Big A

The Keens that jojo posted were perfect for the Galapagos trip. In fact, pretty much everyone was wearing them. You need something with hard toes for some of the rockier landings. If I remember correctly (it was some years ago), we did the hikes in our Keens too and it was fine. The hikes were mostly paths.

I have never been to the Galapagos so I'm not entirely certain what water landings might look like. Personally I like a water shoe if I'm scrambling over coral and rock (think Big Island of Hawaii coastline) where I need to make sure I'm not slipping around in the shoes. Plus sand and pebbles don't wiggle between feet and shoe and cause pain.

I'm guessing maybe they bring you near the shore in small boats and you're expected to walk through the water to the island. Will you have a backpack? If so, I'd put my hiking boots in the backpack and wear my water shoes (which have a loop on the back). Then when I change on shore, I'd clip my water shoes to the outside of my backpack with carabiners while I hike around. I've done something similar with flip flops and Tevas for backpacking when there were stream crossings necessary.

Thanks for all of the great suggestions. Yes, we will have backpacks so can trade out shoes and place them in our backpacks.