A must go in Guatemala. You have this huge lake with small villages all around. It's touristy but the locals are pretty kind and you have a lot to do. I met many people who were there for the 3rd, 4th or 5th time! You have great spanish lessons opportunities and Volunteering Work. We stayed San Pedro, in Hotel S. Francisco Q20/person/room but you have tons of options closer to the lake. In San Pedro you have the better night life, a street with few bars with music for all tastes. You can be easily invited for house parties and trance parties :) Besides swimming in the lake and just chilling all day you can go cannoying around the lake. Hike San Pedro volcan for the sunset or sunrise. Try the delicious chai of Shanti Shanti, while you have a great view to the lake. You can get a boat to Santiago for a day trip (or you can stay there overnight) and hire a tuk tuk driver for an hour to show you the must of the place. They have this weird ritual of a statue drinking alcohol and smoking tobacco... we still don't know if it's a real thing or something just for tourists (you only pay Q5 to get in).