I believe Costa Rica has no deserts. Almost all of the interior of Costa Rica is mountains that are blanketed in jungle/forest. Also it has around 7 active volcanoes depending on how you'd define an active volcano, one of the more popular ones is the Poas Volcano which i believe is a national park. As for beaches, Costa Rica is surrounded completely on 2 sides by the Pacific on the West and the Gulf of Mexico on the East.
