Arenal volcano is the most spectacularly active in Costa Rica. Many people visit this park at night to watch the lava flows and red hot boulders ejected from the volcano glow in the darkness. Although eruptions are the main attraction, you should be aware that even in the dry season the clouds sometimes obscure the top of the volcano, and your chances of seeing a pyroclastic display are lessened in the rainy season. Volcano watching is better than a fifty-fifty proposition, but you should plan on taking advantage of some of the other attractions in the area, and consider it a bonus if you see Arenal put on a huge display.