Since I left the South American continent via Cartagena, Colombia, I started Central America and did all countries....Panama, Costa Rica, Nicaragua, Honduras, El Salvador, Guatemala, and Belize.
I spent more time in Costa Rica (21 days) than in any other country, followed by Guatemala and Nicaragua. I enjoyed Costa Rica the most - rain and cloud forests, active volcanoes, gorgeous beaches, coastal villages, nice people, and awesome animals roaming in the many national parks. Having had several close up encounters with sloths and tapirs in their natural habitat was the highlight of my visit to Costa Rica.
Second, Guatemala with its people!, Mayan villages, great culture, active volcanoes, and colonial towns. Third....Nicaragua, the highlight was doing the 5-hour climb up Volcano Conception on the Island of Ometepa in Lake Nicaragua. This probably was one of the top 3 mountain climbs of my life!
I really didn´t spend enough time in Honduras, El Salvador, Belize, and Panama to evaluate these countries. The little I experienced in Honduras (Copan Mayan Ruins) and southern Belize (Punta Gorda and staying at the Mayan Village of La Laguna) was great!
While there is so much to experience in all of Central America, you no doubt will find garbage strewn around villages, towns, cities, and along the highways. This is a true eye sore and such a shame that these people have so little respect for nature and for others. Nicaragua and El Salvador was probably the worst, with Honduras and Guatemala in second place. Costa Rica was not bad at all. Further down south (South America), Colombia is the worst polluter!
If I ever return to Central America, I would want to explore the hard to reach coastline all the way from the Yucutan (Mexico) down the Caribbean coast of Belize, Honduras, Nicaragua, Costa Rica, Panama and by boat around the San Blas Islands of Panama to the colonial town of Cartagena, Colombia. While this would be a fantastic trip, it will be very time consuming and expensive, and will need very careful planning. Most of the coast of Honduras and Nicaragua is only reachable by foot and boat. Maybe one day!