With a diameter
of 1.5 km., the active crater is reportedly the widest
of any volcano in the world. If it is clear enough
to see to the bottom of the 300-meter deep crater,
you will surely observe some type of activity ranging
from fumaroles to bubbling emissions on the surface
of the small rain-filled lake to actual geyser-type
eruptions, but it is constantly changing. During the
early 1990s, there was enough geyser activity to cause
the lake to lose its water by the end of the dry season
(April/May); this resulted in increased gaseous emanations
that forced the park to close on a few occasions.
Looking to the
left of the crater you can see the deleterious effects
of the volcanic gases that cause a localized form
of acid rain. For several kilometers downwind from
the crater the vegetation is brown and dying.
A few meters back
down the trail from the active crater overlook, a
1.5 km. trail leads off to Lake Botos, a densely forested
dormant crater filled with rain water. A portion of
this trail goes through an eerie-looking section of
stunted forest. The trunks and branches of the small
trees here are gnarled and twisted from the harsh
climatic conditions in exposed areas at high elevations.
At the Lake Botos overlook you'll be near the highest
point in the park which is 2,704 meters.
At this elevation
wildlife is not particularly abundant, but there is
usually a fair amount of bird activity. Some of the
more common species are the Fiery-throated Hummingbird,
Sooty-capped Bush-Tanager, Slaty Flowerpiercer, Mountain
Eleania, Black-billed Nightingale-Thrush, and Black-and-yellow
Silky-Flycatcher.
Given its high
visitation, the National Park Service has chosen Poás
as a model park. One of the benefits of this is the
Visitors' Center which presents a thorough explanation
of vulcanism and the natural history of Poás using
a variety of entertaining and informative displays.
Climate: It
can get cool at this 2,500+ meter elevation, so layers
are advised. If it is sunny, use plenty of sunscreen
because the thinner air lets the UV rays through even
more intensely than if you were at the beach. Mornings
tend to be clear, but the clouds can build up quickly.
The driest months are from January to April.
