What kind of shoes to bring to Nicaragua?

I usually put sandals or huaraches in my bag because I can squash them and make them pretty small, then wear another pair of shoes on my feet while on the plane. (Huaraches can pick up a lot of small pebbles, grit, and gravel.)

One good thing I discovered on my recent trip to Nicaragua is that you can buy t-shirts really cheap in the 'paca' stores, so you might consider taking fewer shirts than you had planned on, to save room.

Sometimes, the backpackers tie shoes by their laces to the outside of their backpacks to save room, I guess.

Also, Nicaragua seems to have plenty of 'Payless Shoe Source' stores (in case you find yourself in need of footwear).

You are definitely fine hiking Mombacho and Masaya with Keens. You can probably do Cerro Negro with minimal difficulty as well but maybe risk getting the small rocks in your shoes.

I hiked all around Mombacho in open toe Tevas...no problem. It's pretty tame.

I went volcano boarding last year on Cerro Negro.

Because all I brought with me were keens, i ended up having to buy a pair of shoes. What's said in #1 is true, there are lots of Payless Shoes type stores. We opted out to going to the super in Leon and buying 'water booties," those neoprene type covered beach shoes which barely cost anything...much cheaper than anything in a shoe store and were super light and compact, but covered your feet.

If you wear your keens on the hike and then put the other shoes on with a good pair of socks, tuck your pants into them, you'll be fine. The thing with volcano boarding is that you don't want the lava gravel to get into your shoes. The open heal design of keens may cause your heals to burn as you're surfing....the heat of the gravel makes it worse.