Volcano Concepcion is very impressive! If you are in or are planning to come to Nicaragua you have to check out Volcano Concepcion. It is a massive active volcano and an excellent day trip.
While we were in the Cafe of our hotel we met a few other travelers that were also looking to hike the volcano the following day. This worked our perfect because we were able to negotiate a group rate ($12.50 per person) for a guide to take us up the Volcano and spend the day with new friends.
If you are an experienced hiker I think you would be fine on your own, but the Island requires that you use a licensed tour guide when hiking up. We went with Luis (Smiley) who is a really knowledgeable guide and very fun.
Check out the video of our hike up Volcano Concepcion: