Arenal Volcano in Costa Rica has maintained consistent activity since the 1960s, ranging from small ash explosions to large eruptions sending hot rocks over 1 kilometer into the air. It stands at approximately 1633 meters tall and offers the best volcano viewing opportunities in Costa Rica due to its reliable activity levels. In 1998, a major eruption caused temporary evacuations from nearby hotels, though the danger passed quickly without injuries.

1. Since that time, Arenal Volcano has maintained nearly
constant activity ranging from soundless explosions with large
mushroom-shaped clouds of ash overhead to booming explosions
sending hot rocks nearly a kilometer into the air to pyroclastic
explosions highlighted by rushing gases and flowing lava pouring
down the side of the volcano. For visitors to Costa Rica, volcano
viewing is the most promising at Arenal – no other volcano has been
this consistently active.
Arenal Volcano rises to approximately 1633 meters at its summit,
although the exact summit height changes frequently due to the
volcanic activity.
One of the major eruptions occurred on May 8, 1998 and gave rise
to temporary evacuations from area hotels, although the danger
quickly passed and no one was injured.