The volcano was asleep for hundreds of years… In 1968 it had an eruption and destroyed the small town of Tabacón… Arenal is considered Costa Rica's most active volcano
We visited Arenal last year around this time and we had beautiful weather during our stay in the area. I was able to snap some clear, early morning pictures of the smoking crater.
Unfortunately, we returned this year to mostly rain and fog. Some cheap ponchos helped us enjoy the outdoors despite the dreary weather.
On the last day, it did clear up a bit (but not enough to see the volcano) and we enjoyed the hot springs at Los Lagos.
The kids striking a pose in front of the hot springs: